macOS 11.0 Big Sur: review

The era of Mac OS X is over. Kind of.

For the first time in almost two decades, Apple has decided to bump up the version number of the Mac’s operating system. The change is meant to call attention to both the pending Apple Silicon transition—Big Sur will be the first macOS version to run on Apple’s own chips, even if it’s not the first to require those chips—and to an iPad-flavored redesign that significantly overhauls the look, feel, and sound of the operating system for the first time in a long while. Even the post-iOS-7 Yosemite update took pains to keep most things in the same place as it changed their look.

But unlike the jump from Mac OS 9 to Mac OS X, where Apple swept away almost every aspect of its previous operating system and built a new one from the foundation up, macOS 11 is still fundamentally macOS 10. Early betas were even labeled as macOS 10.16, and Big Sur can still identify itself as version 10.16 to some older software in order to preserve compatibility. Almost everything will still work the same way—or, at least, Big Sur doesn’t break most software any more than older macOS 10 updates did. It may even be a bit less disruptive than Catalina was. This ought to be a smooth transition, most of the time.

We won’t be making any major changes to how we approach this review, either. We’ll cover the operating system’s new look and new features—the things that any Big Sur Mac will be able to do, regardless of whether it’s running on an Intel or an Apple Silicon Mac. To the extent that it’s possible to do without final hardware in-hand, we’ll cover the new macOS features that will be native to Apple Silicon Macs and outline how the software side of the transition will go.

System requirements and compatibility

2013-era Macs like this MacBook Air are the oldest things that Big Sur will officially run on.
2013-era Macs like this MacBook Air are the oldest things that Big Sur will officially run on.

Starting with Sierra, Apple has begun dropping support for big groups of Macs every other year—last year, Catalina ran on almost everything that could run 2018’s Mojave. But Big Sur drops support for all 2012 Macs and a couple of 2013 models. Here’s the official support list:

  • MacBook (2015 or newer)
  • MacBook Air (2013 or newer)
  • MacBook Pro (Late 2013 or newer)
  • Mac mini (2014 or newer)
  • iMac (2014 or newer)
  • iMac Pro (2017)
  • Mac Pro (2013 and later)

This list eliminates support for all Macs with Intel’s 3rd-generation Ivy Bridge processors, all Macs with 802.11n Wi-Fi, and most Macs that still use Nvidia GPUs (the late 2013 15-inch MacBook Pro being the lone holdout). The floor for Big Sur is generally a 4th-generation Haswell processor and a Metal-compatible GPU from Intel or AMD, plus the Apple Silicon Macs when they begin arriving.

When past macOS releases dropped support for older models, there was some kind of hardware-related reason for it—Lion required a 64-bit Intel processor, and Mojave required a Metal-compatible GPU, for example. But more recently Apple has taken to dropping support for Macs right around the time when they become “obsolete,” according to the company’s tech support policies. Anything that Apple stopped selling more than seven years ago is considered “obsolete,” and those devices can’t be serviced at an Apple Store or through Apple’s mail-in repair service. While there are exceptions, such hardware usually won’t be officially supported by newer macOS releases, either.

Setting aside broader objections to how Apple handles software support—there’s no readily apparent reason why a Mac that runs Catalina wouldn’t be able to run Big Sur—the unluckiest Mac this year is the 2013 iMac. These models have the exact same CPUs and GPUs as other 2013-era Macs that are still supported, but Big Sur won’t run on them without modification. Apple won’t answer questions about why this or that specific Mac model did or did not make the support list, but the hardware in these iMacs is virtually identical to the still-supported late 2013 MacBook Pros. If you’re thinking that it doesn’t make sense, I agree with you.

What should I do with my unsupported Mac?

If you’ve got an older Mac that you’re still happy with, you have some options. You can continue to run Mojave or Catalina, depending on which version you’re happiest with. Apple typically supports the previous two versions of macOS with security updates and new Safari versions, so Mojave should be supported for another year and Catalina should have two years of patches left. Apple may make some changes to iCloud or other services that break certain functionality (changes to apps like Notes, Photos, and Reminders have, in the past, made them unable to sync correctly with older versions of macOS and iOS), but the operating system itself and most third-party apps will continue to work fine—and you’ll still be reasonably secure.

Another option, particularly if you’re using a Mac that is no longer officially supported but does have a Metal-compatible GPU, is to wait for a patching tool. These enable older Macs to run newer versions of the operating system by circumventing some compatibility checks and re-adds drivers that Apple stripped out of the operating system. Forum threads suggest that 2012 and 2013-vintage Macs run Big Sur just fine, though Wi-Fi and Bluetooth support appears to have been removed. Using a patching tool can lead to instability, and it means you’re relying on community members working in their free time to keep your Mac supported and to keep updates from breaking things. That wouldn’t be my first choice. But if you want Big Sur and you just can’t afford a newer computer right now, it might be a viable option if you make sure to keep your most important data backed up somewhere. Dosdude1 has been releasing macOS patchers since Sierra in 2016, so keep an eye on his site and hopefully a Big Sur patcher will show up there if there hasn’t been one already.

A third, less satisfying option is to install another operating system—this is probably the best way to go if you’ve got an older Mac that was dropped in Sierra or Mojave and doesn’t include a Metal-compatible GPU. Nothing should keep Windows 10 or most Linux distributions from running on these Macs, though you may run into trouble finding modern drivers for the oldest systems. The home version of Neverware’s CloudReady operating system can turn most older Macs into ersatz Chromebooks, which is a decent fit for computers with older processors and 2 or 4GB of RAM. All of these will take you out of Apple’s software ecosystem (aside from the limited browser-based iCloud apps and iCloud for Windows), but they’ll keep your old computers (relatively) secure and functional.

Other system requirements

Because it drops support for quite a few older Macs, some features that didn’t work on older Catalina Macs will now work on all Big Sur Macs. That includes WPA3 Wi-Fi encryption support and Apple Watch unlocking.

One macOS feature that still requires a newer Mac is Sidecar, the Catalina feature that allows you to use an iPad as an external monitor for your Mac. Because it relies on hardware acceleration support for HEVC video encoding, it is restricted to Macs with 6th-generation (Skylake) or newer Intel processors. In Macs with Apple T2 chips, the T2 handles this encoding instead. That list of hardware includes:

  • MacBook (early 2016 or newer)
  • MacBook Air (2018 or newer)
  • MacBook Pro (2016 or newer)
  • Mac Mini (2018 or newer)
  • 27-inch iMac (late 2015 or newer)
  • 21.5-inch iMac (2017 or newer)
  • iMac Pro (2017)

There are other macOS features that require a newer Mac with an Apple T2 chip, like always-on Hey Siri support, Activation Lock4K HDR streaming support, and more secure booting that prevents loading unsigned operating systems or booting from external drives by default. But since most of those are not unique to Big Sur (and since some of them could be described as “restrictions” rather than “features”) we won’t cover them here. And, of course, only Macs with Touch Bars and Touch ID buttons benefit from any changes or improvements that involve either of those features (not that there have been any to speak of in this release).

Branding, installation, and free space

Big Sur
Big Sur’s main wallpaper.

Last year I wrote a lightly unhinged rant about Apple’s post-cat naming scheme for new macOS releases, and I suggested that the next release be named after a California location that was not as rock-centric. (In my defense, I was helping a newborn through a lot of sleepless nights at the time.)

Big Sur doesn’t really break the cycle, as it’s a stretch of California’s coastline where the Santa Lucia mountain range meets the Pacific Ocean. The rocky shoreline aesthetic is in line with Catalina’s general look and color scheme. But Big Sur is, at least, a bit more verdant than the rocky Santa Catalina Island. There is grass, and there are trees. Those things are all growing on big rocks, but it’s a step in the right direction.

This year, we dug into the files on old Mac OS X install discs to find install icons going all the way back to version 10.0. Though design of the physical discs themselves changed in the early days of Mac OS X, the icons themselves didn’t start changing until version 10.4.
This year, we dug into the files on old Mac OS X install discs to find install icons going all the way back to version 10.0. Though design of the physical discs themselves changed in the early days of Mac OS X, the icons themselves didn’t start changing until version 10.4.

The change in operating system version or app icon design doesn’t affect Big Sur’s install icon design or the operating system’s branding. Round icon, thumbnail of the desktop wallpaper, arrow pointing down. I suspect future versions of macOS may move to a rounded square icon, the same as every other app in Big Sur, but it hasn’t happened this time.

The setup process in Big Sur will still be pretty familiar for most Mac owners, but it
The setup process in Big Sur will still be pretty familiar for most Mac owners, but it’s more rounded and colorful and the staid gray background has been traded for a colorful smear.

The install process for Big Sur is mostly the same as for the last few versions of macOS; download the installer from the Mac App Store and then run it to upgrade. It’s still possible to create a USB installer for Catalina if you’ve got a slow Internet connection and a lot of Macs to upgrade, but that feature is slowly becoming less convenient than it used to be since Macs with the Apple T2 chip can’t boot from external media by default and any Mac with a T1 or T2 typically needs to connect to the Internet during setup anyway so it can download and install updates for the BridgeOS software that makes them work.

The setup screens in iPadOS 14 look more than a bit like the ones in Big Sur.
The setup screens in iPadOS 14 look more than a bit like the ones in Big Sur.

The macOS setup screens are mostly brushed-up versions of the ones you’re used to, albeit with Big Sur’s new rounded corners and smearily colorful background rather than the typical staid gray. It’s striking, actually, just how closely the look of the macOS setup screens mirror the ones in iPadOS 14—you’re still setting up very different devices that are asking different questions, but the visual similarities really drive home how similar these two different kinds of devices will be once Apple Silicon Macs arrive.

Big Sur needs bigger disk space

The other big difference between Catalina’s install process and Big Sur’s is that Big Sur requires more space—quite a bit more, actually. The release candidate build of Big Sur’s installer is 12.23GB, nearly half again as large as the 8.26GB installer for macOS 10.15.7. The size of the macOS installer has been creeping up steadily for years, from 4.78GB for macOS 10.12.0 (a recent low point) to 6.02GB for 10.14.0 to 8.09GB for 10.15.0. The jump from Mojave to Catalina was the biggest size increase in recent memory, and the jump from Catalina to Big Sur is even bigger.

Installer sizeSize of new system partition
macOS Catalina (10.15.7)8.26GB11.08GB
macOS Big Sur (11.0.1 RC2)12.23GB14.94GB

A fresh, fully indexed installation of Catalina 10.15.7 takes up 16.39GB of space on a 2016 13-inch MacBook Pro, counting the 11.08GB main OS volume, the 3.5GB user data volume, the 81.9MB preboot volume, and the 528.9MB recovery volume, but not the volume used for virtual memory). A fresh installation of the Big Sur release candidate uses 19.06GB of space on the same computer, across a 14.94GB system volume, 3.06GB user data volume, 655.4MB recovery volume, and an 283.6MB preboot volume. That’s a roughly 4GB increase in size for the system partition, and a 3GB increase overall. Whether that’s coming from new iOS frameworks or other files required to support Catalyst, code related to Apple Silicon Macs, or something else, that’s a significant step up.

I bring all of this up primarily because many Macs defaulted to 128GB of storage for an embarrassingly long time—the baseline was bumped up to 256GB only this year with 2020’s MacBook Air and Pro and Mac mini refreshes. If you rely heavily on iCloud or external storage and you don’t have a bunch of large apps installed, this is a livable amount of space. But I suspect Big Sur’s extra space requirements—both to install it, and then to run it—are going to be painful for some Macs, especially since SSDs generally start to slow down as they get full.

A funeral for Mac OS X

So long, Mac OS X.
So long, Mac OS X.

Version numbers are a construct, and they don’t confer any specific meaning or power on their own. The first two macOS 11 developer betas were labeled “macOS 10.16,” and macOS 11 is a whole lot more similar to macOS 10.15 than 10.15 is to 10.0. Accordingly, Apple has made a way smaller deal about the jump from 10 to 11 than it did the jump from 9 to 10—understandable, given that Mac OS X was intended as a very bold, confident statement that years of Mac OS vaporware, false starts, and broken promises had come to an end.

If Apple won’t do it, then it’s up to us to give Mac OS X a funeral of its own.

Mac OS X 10.0 was released in March of 2001, but its history goes back to 1997, when Apple bought a company called NeXT and brought a promising operating system called NeXTSTEP and a guy named Steve Jobs into its fold. Following the abject failure of the Copland project and two time-buying backstop releases in Mac OS 8 and Mac OS 9, the actual public release of a new next-generation Apple operating system was a symbolically significant step forward for the company’s late-’90s-early-2000s turnaround effort.

But as an actual operating system, Mac OS X was pretty rough. This came through in reviews like ours, and Apple tacitly admitted as much. Version 10.1 came out just six months later, and Apple continued shipping Mac OS 9 as the default operating system on every Mac until January of 2002. Not exactly a ringing endorsement. But frequent updates and continuous iteration quickly changed Mac OS X into a usable and then enviable operating system, especially against the backdrop of Windows XP’s endless reign and Windows Vista’s early stumbles. Mac OS X would go on to provide the foundations for Apple’s iPhone OS, which itself is the root of iPadOS, tvOS, and watchOS. These days, the iPhone contributes more to the Mac than the other way around.

With the benefit of hindsight, and knowing what we now know about the Mac’s transition from Intel to ARM processors, we can split Mac OS X’s lifecycle into at least three distinct phases:

  • Versions 10.0 to 10.4: Birth and adolescence. These releases took Mac OS X from a rough proof-of-concept to a usable desktop operating system that helped the Mac transition away from classic Mac OS. Version 10.4 also ushered in support for the first Intel Macs.
  • Versions 10.5 to 10.10: Maturity. Every Mac OS X release through 10.5 made noticeable changes to the still-evolving Aqua aesthetic, but things settled down in Leopard and evolved much more gradually after that. In this phase, Mac OS shed the Classic compatibility environment for old Mac OS apps, ended PowerPC compatibility, completed the transition from 32- to 64-bit, added iCloud support (and an increasing number of other iOS features), made significant improvements to power usage and battery life, and more. In Yosemite, the operating system (by then called “OS X”) got a significant but not totally unfamiliar new look that it used until the end of its life.
  • Versions 10.11 to 10.15: The transition. Latter-day releases of OS X (which became “macOS” starting in 10.12) began making gradual foundational shifts that, in retrospect, have made it possible for Apple to transition away from Intel chips to its own processors in a smooth and orderly fashion. Version 10.11 added support for Metal, Apple’s in-house graphics API. Versions 10.12 and 10.13 started the transition to APFS, Apple’s long-awaited filesystem upgrade, which itself enabled all kinds of new features and security enhancements. And version 10.15 ended support for 32-bit apps while adding technologies to allow macOS and iOS apps to share more code. These later, transitional releases have made the foundation of macOS a bit more like iOS, and the things that have been removed reduce the number of legacy apps, APIs, and software that Apple Silicon Macs will need to support. Rosetta 2 doesn’t need to support 32-bit Intel code, because even Intel Macs running Catalina or Big Sur can’t run it; OpenGL and OpenCL were deprecated years ago, reducing the number of apps that rely on them; old drivers and kernel extensions are slowly going away in favor of new System Extensions and DriverKit.

It’s a little premature to eulogize the operating system formerly known as Mac OS X. It will enjoy a long sunset period, including a couple of years’ worth of security updates from Apple and app support from third-party developers for a few years after that. (Just as many Windows 10 apps continue to support Windows 7 and 8, macOS 11 and later versions of macOS 10 will be able to run most of the same apps for a long time to come). It will gently fade away until one day, apropos of nothing, you realize that you just don’t see it around anymore. It was born with great fanfare and will pass away with little.

Steve Jobs talks about the last macOS version number change.
Steve Jobs talks about the last macOS version number change.

Still, it feels like the end of an era. The first Mac OS X release happened seven months before the release of the first iPod. It persisted through one processor transition, the iPod’s introduction, then the iPhone’s, then the iPad’s, as well as the Apple Watch, MobileMe, iCloud, Ping, Apple Music, three wholly separate iterations of the Apple TV hardware, Apple TV+ the service, Steve Jobs’ passing, and countless new PowerBooks, iBooks, Power Macs, Mac minis, iMacs, eMacs, MacBooks, MacBooks Pro, MacBooks Air, Mac Pros, and the iMac Pro. It saw me through high school, then college, then four different jobs across two career paths (and a bunch of freelancing, besides). I wrote the review of the last version of Mac OS X frantically in furtive two- and three-hour bursts as my weeks-old baby slept on the other side of the room.

So rest in peace, Mac OS X, pronounced “ten” and not “ecks.” We knew ye pretty well, actually. It was a good run.

Only mostly dead: macOS 10.16 lives on

While Big Sur is indeed macOS 11.0 for software compatibility reasons, Big Sur can still identify itself as the version 10.16 when it needs to. Howard Oakley at the Eclectic Light Company has a good explainer on this, but I’ll recap it in brief.

When some macOS software runs, it runs a quick system check to determine if the macOS version is new enough to run the app. Because macOS has been on version 10-point-something for so many years, that code often just looks at the minor version number to determine whether it can run—version 9 and higher would mean it would run on Mavericks and newer, version 12 and higher would mean it would run on Sierra and newer, and so on. But when software does this in Big Sur, it could get confused, since it would only see that the system’s minor version number was 0; the code would assume that the version being run was 10.0, and not 11.0.

To avoid totally breaking this software for no good reason, Big Sur can identify itself as macOS 10.16 to apps or scripts that request the version number this way. It shouldn’t be a problem for newer apps built with post-Big Sur versions of Xcode.

Other operating systems have similarly played fast-and-loose with version numbers to prevent compatibility problems like this. When Windows Vista bumped the version number from XP’s 5.2 to 6.0, it broke a lot of apps that were confused by the new number. To avoid doing this again, Windows 7 was actually Windows version 6.1, Windows 8.0 was version 6.2, and Windows 8.1 was version 6.3 (Windows 10 bumped the internal version to 10.0, after Microsoft made changes to the way Windows reports its version numbers to older apps).

What numbers are next?

If Apple’s changing the version number from 10 to 11 this year, then what happens next year? Will we be talking about macOS 11.1 in the summer of 2021, or will Apple begin bumping the major version every year as it does with iOS?

We don’t know this for sure, but we do know that the release version of Big Sur is actually macOS 11.0.1. That number format could just be for software compatibility reasons like the ones we just talked about, but that Apple has labeled Big Sur’s first major bugfix update “11.0.1” and not “11.1” (as is the style for iOS) at least suggests that macOS will stay on version 11 for some time to come.

A new look

Big Sur brings a brand new look to macOS.
Big Sur brings a brand new look to macOS.

There are two ways to think about how Big Sur changes the Mac’s look and feel.

If you’ve been using Macs for a long time, imagine a slider that goes from one to ten, with “Snow Leopard” at one and “iPad OS” at ten. If post-Yosemite macOS releases set that slider at around a four, Big Sur dials it up to around six. Maybe 6.5.

You could also compare it to the way Apple has developed iPadOS in the last two or three years—adding a dock, improving multitasking, and implementing more robust keyboard and mouse support. Those changes have added Mac-ish flourishes to the iPad without making it not the iPad. Big Sur makes the Mac a bit more iPad-y without making it not the Mac.

The basics: App windows

In some ways, Big Sur changes the fundamental look and feel of the Mac more significantly than any update since the early days of Mac OS X. In others, it remains visually and functionally identical to Catalina. Overall, Big Sur feels familiar, but not all the changes will be to everyone’s taste.

Let’s begin with the basics: the way that app windows overlap and interact on-screen. An important distinction between macOS and iPadOS is the Mac’s windowed multitasking, which calls for stronger use of shadows (to show what is on top of what) and a clear delineation between active and inactive app windows. Windows need to be able to show alerts and prompts and file pickers when necessary.

The first thing you’ll notice about Big Sur windows is that Catalina’s gently rounded corners have become even rounder, closer to the corners of an iPhone X or late-model iPad Pro screen (Mac screens don’t have rounded corners yet, but no one should be surprised if it happens in some future Apple Silicon Mac). Windows in general are brighter than in Catalina, with lighter title bars (for apps that have them).

Window shadows work the same way they do in Catalina—all windows have a light shadow surrounding them, and the active window has a slightly deeper and more noticeable shadow under them. The size and opacity of the shadow doesn’t change in the move to Big Sur, even as windows themselves get a hint brighter and flatter.

To describe the new Big Sur window style as “flatter” wouldn’t be quite right, since post-Yosemite windows don’t have much texture to them anyway. But there is a reduction of contrast between drop-downs and buttons and other controls and the surrounding window chrome. Note how much less distinct the controls in the TextEdit app look in Big Sur, even though the window is active. If there’s one change Big Sur makes that is objectively negative rather than just different, it’s this reduction in contrast, which makes for nice consistent-looking app windows in screenshots but makes it harder to see where controls actually are when you’re trying to get things done. And since reducing contrast is a tool macOS already used to help you distinguish between an active and an inactive window, making active windows less contrast-y makes it that much harder to tell the difference at a glance.

Finder windows show off a few specific elements new to Big Sur:

  • Removal of the title bar—Apple calls these “unified” app windows. Big Sur apps still can have dedicated title bars, as visible in the Terminal and TextEdit, but in other apps the titles have been collapsed and inserted amongst the rest of the controls.
  • The stoplight buttons have more padding around them, especially noticeable on the top and left sides. This look is generally just used for these new unified app windows, though some apps that already weren’t using title bars may need tweaks to correct for the extra padding (this was an issue for older versions of Chrome and Edge running on Big Sur, though it appears to be fixed now).
  • The sidebar now stretches, uninterrupted, across the entire left edge of the window. Other apps, like Notes and Mail, show an even more pronounced version of this—they take advantage of the lack of a dedicated title bar to build windows with three top-to-bottom columns that can each have their own controls.
  • All icons and controls across the top of the window and the sidebar have been replaced with SF Symbols vector graphics that have been designed to work well with the system’s San Francisco typeface, accessibility features, and accent colors.
  • Buttons are less button-y, which is probably the most distinctly iOS-ish design choice here. Button borders don’t exist unless a button is pressed (or, as when you use iPadOS with a mouse or trackpad, when you hover over it ).
Don’t be shy, little icon.
  • You might notice that the small “proxy icon” that used to live to the left of a window’s title in the title bar has disappeared. You can still hover your cursor on window’s title to bring that icon up, but it adds time to the interaction, and it’s awful for discoverability; hopefully there will at least be a toggle somewhere in the System Preferences to fix this at some point. Some apps that retain title bars, like TextEdit and Terminal, still show these icons by default.

Mojave was the first macOS version to include Dark Mode, and with it, the option to change macOS’ default accent color from the classic blue-or-graphite to one of six other colors. Big Sur adds a twist, with a default multicolored option that lets different apps use differently colored icons. You can see this in the sidebars of different built-in apps—like Books or Notes with its yellow accent, or the Finder with its blue accent. App developers make these choices, and you can’t choose different accents on an app-by-app basis. But if you pick a systemwide accent color, it will generally override the developer’s accent color choice. I doubt this will be a particularly noticeable part of Big Sur’s user interface. Even Apple’s apps overwhelmingly default to the classic blue or ignore the setting altogether (as the Podcasts and Music apps do).

Buttons and controls

Buttons, boxes, sliders, drop-down boxes and progress bars don’t change dramatically in Big Sur—they’ve all been tweaked, but they look more or less like they have since they lost their old glassy appearance in Yosemite.

Checkboxes and radio buttons both look mostly as they did before, but with more rounded boxes and bolder checks for checkboxes and larger inner circles for radio buttons. Progress bars lose a little contrast, with softer outlines. The filled-in part of progress bars is now rounded on both ends, rather than rounded on the left end and flat on the right side.

Tabs within windows (like the ones embedded in many preference panes) also look different. It’s easier to look at the differences than it is to describe them, but overall they look less like distinct buttons separated by dividers and more like highlighted text labels in one continuous strip. The highlighted tab doesn’t use your selected accent color, either—the active tab is a brighter white in Light Mode or a lighter gray in Dark Mode.

The look of sliders is substantially changed, too. The downward-pointing arrow has been replaced by a narrow oval, and the little ticks below the sliders are now integrated into them. Drop-down menus have been gently rounded, too, and the button you click to make them drop down now has a small layer of padding around it (this is common to menus throughout the operating system).

Finally, let’s talk about buttons. Like most things in Big Sur buttons throughout the operating system get just a little more rounded. And Apple has introduced a second, larger standard button size, most visible in system alerts and dialog boxes. They’re taller and wider than typical buttons, and you’ll see them the most frequently in windows that are asking you to choose from among a few different options.

Dialog boxes and alerts

Speaking of Big Sur’s new dialog boxes, these are the single most iOS-y thing about the new operating system and probably the most jarring of all its visual changes. Both standalone system-generated dialog boxes and dialog boxes generated by individual apps have been redesigned, as have file picker boxes that show up when you try to open or save a file from within an app.

All of these new dialogs appear as rounded squares or rectangles with larger buttons than before, center-aligned text, and text and buttons that spread out vertically rather than horizontally. For standalone system dialogs, these alerts are translucent boxes that pop up in the middle of your window. They no longer have title bars—the alerts in Catalina didn’t actually have titles in their title bars anyway, it was just a strip of window that you could click and drag. In Big Sur, anything above the text (including the icon) can be clicked and dragged.

In-app dialog boxes work sort of the same way, but instead of springing up in the middle of the desktop they pop up in the middle of the app window. In Catalina and older versions of macOS, these dialogs would slide down from the top of the window, dimming the title bar but none of the other content and remaining “attached” to the window that generated them at all times.

Big Sur’s equivalent dialogs act much more like they do in iOS, springing up as separate windows that dim the entire app window behind them.

As with many things in Big Sur, this doesn’t really change how these dialog boxes behave—you can still click and drag the window that generated the dialog box without closing that dialog, for example, even though the app window appears to be out of focus and totally inactive. But I’m not really sure that vertically oriented dialog boxes work as well on Macs (which exclusively have screens wider than they are tall) as they do on iDevices (which generally have screens taller than they are wide).

I have yet to see a Big Sur dialog box that is unusably tall on a 13-inch screen, and if it’s a problem you’re having with your app, it’s possible that you may be trying to present too much information at once anyway. But by the time you have a short paragraph of text and three or four buttons in a box, they do start to look a bit weird. And if your alert box has so much text in it that it won’t all fit onscreen at once, Apple will add a scroll bar rather than let the box extend beyond the borders of your screen.

New icons (or: it’s hip to be square)

Post-Yosemite app icons for the default macOS apps fell into four broad categories: round ones like Photos or Safari; square ones like Terminal or System Preferences; squares at jaunty diagonal angles like Mail, Calendar, or Reminders; and ones that were shaped like an object related to their function like Home’s house, Disk Utility’s disk-and-stethoscope, or Messages’ speech bubble. These icon types could sometimes have some other object superimposed over top of them, like Preview’s inkwell or TextEdit’s pen.

Big Sur strives for consistency in its default app icons, transitioning across the board to iOS-style rounded squares. Even now-obscure apps like the DVD Player or Screen Sharing have gotten redesigned rounded-square icons.

Some of these new icons are more successful than others. Some apps, like Messages and the App Store, move to an iOS-style icon design with stronger shading and texture, conveying a sense that these are the apps you know from iOS, but different. Others, like Calendar or Notes, use icons that are essentially indistinguishable from their iOS counterparts. And still others retain their Mac-ness by superimposing an object over a rounded square. The best of these, like Preview or TextEdit, use an object that references the app’s purpose. The worst ones, like Automator or Chess or Disk Utility or System Information or any number of others, just superimpose some element of the old icon over the top of a new one and call it a day.

I don’t mind the uniform shape of the new icons so much as I mind the inconsistent approach. Why do some iOS icons get extra shading while others don’t? Why is Automator literally just the old Automator icon on top of a square? Why superimpose objects over the top of some icons and not others? In the future when we’re all regularly running iOS and iPadOS apps on our Apple Silicon Macs, all the icons will look more or less like they all belong together—I would guess that this is the driving force behind this change.

The longstanding "X" on the System folder, which hung around even after "X" was dropped from macOS
The longstanding “X” on the System folder, which hung around even after “X” was dropped from macOS’ name, is now gone in version 11.

Other longstanding icon designs also get a refresh in Big Sur, though only app icons are apparently required to be rounded squares. Icons for internal and external drives and networked volumes have all been made shinier and more rounded, and folders have gotten more rounded and bubble-ish. Folder icons are actually one place in the operating system where contrast has increased—the embossed icons on some system folders are now darker than before, and the folder tabs in the background are now darker than the front of the folder in the foreground, rather than being lighter. Note that the “X” icon on the System folder has been replaced with “macOS,” in keeping with the version number bump.

Control Center and Menu Bar

Andrew Cunningham
Andrew Cunningham

The Control Center is one of the better iOS-inspired features that macOS has picked up, revamping the top-right portion of the menu bar and providing access to a wider range of common controls. Like its iOS counterpart, it’s customizable—there are some controls that always appear in the Control Center, but others can be added or removed, and most of them can be moved directly into the Menu Bar for easier access.

A new Dock & Menu Bar preference pane combines all of the old Dock settings with all of the new Control Center settings, and it’s where you’ll customize all your controls. It’s a handy place to access menu bar settings for things like the Bluetooth and volume menu bar items (though they’re still accessible in their respective preference panes, too). Whether you access them from the Control Center or the Menu Bar, these controls work the same way, though obviously placing them in the Menu Bar instead of the Control Center will save you a couple of clicks.

Customizing the Control Center.
Customizing the Control Center.

Here are the controls that are required to appear in Control Center. For all of these, you can optionally add or remove their icons from the Menu Bar, and some have additional options that will show or hide those Menu Bar items all the time or just when they’re active. We’ll denote which controls can be option-clicked for more information or settings.

  • Wi-Fi, which displays your current network, a list of currently accessible networks, and a link to the Network pane in System Preferences. Option-click to access logging and diagnostic options, and to view IP and MAC addresses, the current transfer rate, other advanced information.
  • Bluetooth, which shows all currently paired and connected Bluetooth devices and (if applicable) their current battery levels. For things like AirPods or other headphones that are paired but not actively connected, you can click them to connect. Option-click to view signal strength and MAC addresses.
  • AirDrop, which can enable or disable AirDrop and control its access settings.
  • Do Not Disturb, where you can mute notifications temporarily or permanently and access the Notifications preference pane.
  • Keyboard brightness, which is a brightness slider for your MacBook’s keyboard backlight and provides a link to the Keyboards preference pane. This control won’t show up on a desktop Mac.
  • Screen Mirroring, where you can see Apple TVs and other AirPlay devices your Mac can send a display signal to.
  • Display, where you can adjust brightness, Dark Mode, Night Shift, and True Tone (if applicable) settings and access the Displays preference pane.
  • Sound, where you can adjust volume, select your sound output, and open the Sound preference pane. Option-click to view and switch between audio inputs as well.
  • Now Playing, which shows you some information about whatever audio or video is currently playing, along with basic playback controls. Click the Now Playing section in the Control Center or the button on the Menu Bar and it will show you all apps that are playing something. Apple’s media apps like Music and Podcasts will show album art with a small app icon on top of them; third-party apps generally just show an app icon.

Three other Control Center modules can appear in either the Control Center or the Menu Bar:

  • Accessibility Shortcuts, which provide quick toggles for some (but not all) of the operating system’s accessibility settings as well as a link to the Keyboard and Accessibility preference panes. You’ll still need to go to System Preferences to customize these if you need to—for example, the Color Filters button will toggle your last-used color filter, but this can’t be used to toggle between all of them.
  • Battery(on Macs with batteries), which shows the battery percentage. This is also where you show or hide the battery percentage at the top level of the menu bar—the toggle is only in System Preferences now, not in the Battery menu itself. The Big Sur battery menu won’t give you the battery’s condition if you option-click; that’s all in the redesigned Battery preference pane now.
  • Fast User Switching, which allows you to switch between user accounts without logging out, or to jump to the login window. In older macOS versions, you’d click your username in the Menu Bar to see this menu; in Big Sur, it’s just an icon.

Four other things can only appear in the Menu Bar, and not the Control Center:

  • Clock, which shows the date and time. The Menu Bar clock’s behavior has changed a lot, which we’ll get into in a moment.
  • Spotlight, which works just like the Spotlight button usually does.
  • Siri, which brings up Siri.
  • Time Machine, which gives you controls and status messages for your Time Machine backups.

The Menu Bar itself changes subtly from its post-Yosemite design. It’s a few pixels taller, the font size is smaller, and there’s a little more vertical padding in the menus themselves. There’s a “large Menu Bar” option in the Accessibility preference pane, which makes the Menu Bar infinitesimally taller. But most notably, Apple has cranked up the translucency on the Menu Bar, which makes it behave differently than it did before.

In Catalina, the Menu Bar’s colors are determined by whether you were using Light or Dark mode and what your accent color is. The Menu Bar was translucent, but objects behind it were blurred and abstracted enough and the translucency effect was subtle enough that it didn’t cause readability issues regardless of the underlying wallpaper.

In Big Sur, the translucency has been turned up enough that Apple now changes the color of the Menu Bar in response to the wallpaper that’s underneath it. A lighter background means a light menu bar with dark text, and a dark background means a dark menu bar with white text, regardless of whether you’re in Light or Dark modes. And the highlight color when clicking menus is just a darker (or lighter) patch of gray, rather than your accent color. The menus themselves respect both your Light/Dark mode selection and your accent color.

I don’t mind how this looks most of the time, though I do prefer the greater contrast you get with the accent color in the Menu Bar to Big Sur’s subtle shading difference. The translucency didn’t cause readability issues regardless of the wallpaper I used, though it’s worth noting that I used Big Sur either on built-in MacBook Retina displays or high-quality computer monitors. A crappier, lower-density display with worse viewing angles, color, and contrast might fare worse, whether it’s the non-Retina screen on an aging MacBook Air or a cheapo monitor you’ve hooked up to a Mac mini. Using the Reduce Transparency setting in the Accessibility preference pane won’t make it look exactly like it did in Catalina, but it will make it a solid white or black bar based on whether you’re using Light or Dark Mode.

Big Sur has done a bit of cleaning on the rightmost section of the Menu Bar, which has gotten messier over time as Apple has added more controls. Staring at my Catalina Menu Bar right now, I see the Notification Center icon (macOS 10.8), the Siri icon (10.12), my username (which doubles as a Fast User Switching shortcut), the Spotlight icon (10.4), and then the clock. Big Sur relocates several of those items to the left of the clock, and it kills the dedicated Notification Center button entirely.

Clicking the system clock now brings up the Notification Center and all your widgets, rather than clock-related settings. The dedicated Notification Center button that used to occupy the rightmost area of the Menu Bar is gone. This is a fine way to condense some buttons, though I bring up the Notification Center with a trackpad swipe every time I use it. If you’re more reliant on the button, at least your muscle memory will still work.

All in all the Control Center and its Menu Bar icons are well-executed handy ways to change many of your Mac’s most common settings. And the Menu Bar pane in System Preferences pulls a bunch of icon toggles into one place (though for convenience’s sake, icons for things like Sound and Bluetooth can still be toggled from within their respective preference panes). It’s a relatively rare change in Big Sur that actually surfaces functionality rather than hiding it. This tweak brings some uniformity and consistency to an area of the operating system that is on your screen nearly all the time but had gotten a little messy over the years as new features were grafted on.

Notification Center and widgets

Speaking of cleaning things up, let’s talk about the messiness of the Notification Center in Catalina. Swipe over or click the button to view the Notification Center, which by default shows you a giant ungrouped list of every single notification you’ve gotten from any app in the past week. Scroll up, and you reveal previously hidden toggles for Do Not Disturb and Night Shift modes. Or hit the Today View tab and see an iOS-ish list of situationally helpful widgets that hide your notifications. Active notifications, like Reminders you really, really don’t want to dismiss until you’ve actually taken care of the things they’re reminding you of, dangle off to the side of the main Notification Center pane. I don’t use the feature super often, and I find myself mildly annoyed by it when I do.

As with the Menu Bar, Big Sur does a decent job of cleaning up and unifying the Notification Center, making it more visually appealing and a bit more useful at a glance. For starters, the two separate tabs for the notification view and the Today View have been eliminated, and the Do Not Disturb and Night Shift controls are gone, too (they’re now safely ensconced in the Control Center, which is a more logical place for them).

Notifications are now grouped based on the app that sent them and are displayed at the top of the Notification Center above your widgets; if you’ve got active notifications already showing on your desktop, the Notification Center and everything in it will slide in seamlessly underneath them.

Catalina’s Notification Center.
Big Sur
Big Sur’s updated notification center.

As much as I like the new design of the Notification Center overall, interacting with notifications themselves has been made more annoying by Big Sur’s tendency to hide things.

Take a notification from Reminders, for instance. In Catalina, you could click the notification to open the app, click the Complete button directly to check the task off without opening the app, hit the Later button to get a short list of options about when you wanted to be reminded, or click the X in the upper-left corner to dismiss the notification without doing anything. In Big Sur, both the Complete button and all of those timing options are grouped together under one Options button, and you need to hover over the notification to see that button in the first place. So if I just wanted to mark a reminder as complete, I have to wait the extra beat it takes for the Options button to appear, click the button, and then click Complete, rather than just clicking the Complete button directly. This won’t be an issue for notifications without built-in response options, but it’s annoying for the notifications that have them.

If Big Sur’s new widgets look familiar to you, it might be because many of them are the same ones you get when you upgrade to iOS 14 and iPadOS 14. It’s not just that they look the same—it’s that, through a combination of Catalyst and Apple’s WidgetKit framework, they are literally the same widgets. The operating systems don’t come with the same complement of standard widgets (macOS gets a clock iOS doesn’t have; iOS has an Apple News widget macOS doesn’t have). But third-party developers can make their own to extend the operating system’s capabilities and fill in gaps.

Scroll to the bottom of the Notification Center and hit Edit Widgets to pull up the full-screen widget-picking interface. For widgets with multiple size options, click the S-M-L buttons to preview them. Click the green plus button on a widget or drag it over to the right side of the screen to add it to the Notification Center, where you can then subtract and rearrange widgets as needed. Right-click widgets once they’re placed to resize them or customize them (when they can be customized).

That new sound you’re looking for

Big Sur’s new look is immediately noticeable, but at least it’s in your face about it. The brand-new sound effects aren’t as important, but they’re definitely more surprising. Macs have sounded the same since the George W. Bush administration, so when you hit an error message or empty the trash and you hear a sound you don’t recognize, it feels strange.

Apple says the new system sounds have all been “created using snippets of the originals,” so some of them will catch your ear in a familiar way despite sounding quite different overall.

System Preferences iconography

The System Preferences iconography gets a refresh just like the rest of the OS, but unlike the other built-in apps, Apple hasn’t made an effort to unify their design. It’s a mishmash of rounded-corner icons, round icons, and freeform shapes (usually stylized or abstracted pictures of real-world objects). The variety does make it a bit easier to tell which preference pane is which at a glance—it’s not consistent, but it works better than some of the awkward half-measure app icons elsewhere in Big Sur.

New wallpapers, plus wallpaper and screen saver UI changes

Big Sur adds a bunch of new wallpapers and gets rid of a bunch more—Catalina’s default wallpapers go all the way back to Yosemite, but Big Sur gets rid of most of the pre-Catalina wallpapers in the operating system. Here’s the full list, including static images, ones that support the Dynamic Desktop feature that changes their colors throughout the day, and wallpapers that can simply change as you toggle Light/Dark Mode:

  • A total of 11 new static photos of Big Sur and environs. One of these can be set as a Dynamic Desktop.
  • Four photos of rock formations that have both light and dark appearances. Where would macOS be without its rocks?
  • Four illustrations of landscapes, all of which can be set as Dynamic Desktops (these same images were added to iOS/iPadOS in the 14.2 update).
  • Two iOS-esque colorful abstract wallpapers, both of which have light and dark appearances. One of these is Big Sur’s default wallpaper.

The two desktop wallpapers that only have light and dark appearances retain the split-screen preview thumbnail that Mojave and Catalina had, but the dynamic desktop wallpapers now have preview thumbnails that show slices from all five of their color schemes. It’s a minor thing, but it looks neat.

Though Big Sur adds and removes no screen savers (the “Drift” screen saver was a Catalina addition I somehow missed last year), the thumbnails for all of the photo collage screensavers have at long last replaced the old ladybug thumbnail. This thumbnail was from a very, very old Mac OS X default wallpaper, and someone at Apple finally realized that it hadn’t actually been included with the OS since at least version 10.7. RIP, ladybug wallpaper.

New login window

Apple has tweaked the look of the macOS login window, as it occasionally does. Mostly it just gets the same coat of paint that everything in Big Sur does—rounder test fields and icons—but user profile icons have been bumped up in size quite a bit. As in Catalina, clicking a user profile shifts the background to whatever that user’s desktop wallpaper looks like. So don’t, you know, create a PNG full of sensitive financial information and set it as your background. (This still doesn’t apply to FileVault-encrypted Macs, which always use the system default desktop wallpaper on their login screen since they can’t read anything on your disk until you unlock them with your password.)

A new look for Recovery mode

Your Mac’s recovery volume (or Internet Recovery, when the local Recovery partition is hosed or nonexistent) gets a redesign the same as the rest of Big Sur. The old Recovery window with its title bar and small icons has been replaced by a rounded rectangle more in line with Big Sur’s system notifications, with large icons and no title bar.

Actually using Recovery mode works the same way it did before, with the same tools tucked away in the same places offering the same functionality. It does pick up Dark Mode support, too—in fact, in my testing, I’ve never been able to get Big Sur’s recovery partition to boot in anything other than Dark Mode. Your mileage may vary.

Other odds and ends

Big Sur
Big Sur’s bubbly dock.

There are other things about Big Sur’s new look that are worth noting even if they’re not visually or functionally important enough to spend much time on.

Like most other parts of the operating system, the Dock’s rounded corners get rounder and more bubbly. There’s also a small, almost unnoticeable strip of space between the Dock and the bottom of the screen, giving it a “floating” look that mirrors the way the dock looks in iPadOS.

Starting with Mojave (and only when using Dark Mode), app windows would pick up a subtle tint based on the color of your desktop wallpaper. You could disable this effect either by enabling Reduce Transparency in the Accessibility settings or by choosing Graphite as your accent color.

In Big Sur, Light Mode windows pick up this subtle tinting effect, too. But there’s a separate toggle for enabling and disabling it, so it’s no longer tied to your accent color and can be toggled without disabling transparency elsewhere in the operating system. Because it’s now a separate toggle, the Graphite accent color no longer disables this window tinting effect automatically, though it still disappears when you’re using the Reduce Transparency toggle.

Because this toggle appears in the General preference pane where the “hide and show menu bar” toggle used to be, the menu bar toggle has been relocated to the Dock & Menu Bar preference pane.

Watch the search field appear and disappear.
Watch the search field appear and disappear.

Finally, app windows in macOS have long been able to dynamically hide and show controls as you resize them. For apps with a Search bar, this box now behaves slightly differently than before. In a full-screen or sufficiently large app window, you still get a full-size Search field. But for smaller windows, the field now collapses into a button that only expands into a Search field when you click it. This decision saves some space and gives the normally space-consuming Search bar a middle state between “totally visible” and “totally not visible.”

Apps: Safari 14

Safari 14 was released for Mojave and Catalina Macs in mid-September when iOS 14 came out, so if you use Safari you’re probably already using it to read this. All three supported versions of macOS get most of the same stuff this time around, unlike past years where some of the tracking prevention features have only worked on the newest version of the OS. We’ll start with the aesthetic stuff and then move on to the under-the-hood stuff.

New tabs, new Start page

Safari’s new new tab page. Favicons in tabs are now enabled by default!

After a few years of including it as an optional feature, Safari 14 finally turns browser tab icons back on by default, the same way virtually every other browser on the planet Earth has continued to handle them. These icons make it easier to tell which of your tabs is which, especially in a crowded window with a half-dozen or more tabs open.

Recognizing that these icons are visually useful and that they save space, Apple has tweaked the way Safari handles windows with lots of tabs. Tabs in Safari 13 have a fixed minimum width of roughly 120 pixels (or 240 on a Retina screen), wide enough to display a snippet of the page’s title. Open more tabs than a window can display, and Safari starts to hide older tabs, so you have to scroll left and right across the tab bar to see all of them. Safari 14’s tabs will get narrower until the page title disappears entirely and all you can see is the site’s icon. This gives Safari 14 tabs a fixed minimum width of around 36 pixels (72 on a Retina screen), so you can fit more of them before you need to start scrolling. Hover over one of these tabs to see a thumbnail of the page, which can be useful if multiple tabs are using the same icon.

If for some reason you prefer icon-less tabs, you can still turn them off in Safari 14’s settings. This also reverts to the previous tab-width behavior.

Safari 14’s Start page gets a facelift, enabling background images (accessible via the small Settings button in its lower-right corner) and increasing the number of Favorites icons from two rows of six to two rows of 12, depending on how wide your browser window is (two rows of six remains the minimum). If you have more than two rows of icons, you’ll still need to click Show More to see the rest of them. And a new Privacy Report box gives you a high-level summary of how Apple’s Intelligent Tracking Prevention features are working; more on that in a moment.

Safari Web Extensions: Porting extensions from other browsers

Starting in Safari 13, the only way to install browser extensions for Safari is through installing an app (from the Mac App Store or otherwise) with a Safari App Extensionincluded. Older Safari extensions written in HTML, CSS, or JavaScript and distributed from outside the Mac App Store were no longer supported, which left Safari at a definite disadvantage relative to the wide extension libraries available for browsers like Chrome and Firefox (and, for most Chrome extensions, the new Chromium-based Microsoft Edge).

Safari 14 gives extension developers a lifeline by allowing them to use the WebExtensions API that allows Chrome and Firefox extensions (and Edge, and Opera, and most browsers based on Google’s or Mozilla’s codebases) to use most of the same code. Using Xcode, you can make Safari Web Extensions by importing your existing Chrome or Firefox extension using a command-line tool provided by Apple. You can create a new Safari Web Extension in Xcode and make it work in other browsers. Apple doesn’t support all the JavaScript APIs that a Chrome or Safari extension might be able to use—Apple’s documentation says that unsupported APIs will typically be ignored, but that developers should check the list of unsupported APIs so they can work around potential incompatibilities.

Apple still recommends using App Extensions “for sharing code between your native macOS app and Safari,” which means it will probably continue to be the best way for password managers and productivity apps to add functionality to Safari. But Safari Web Extensions at least provide a bridge between Safari and the extensive extension libraries of other desktop browsers. Whether developers actually use it remains to be seen.

The Privacy Report and Intelligent Tracking Prevention

Introduced in Safari 11 running on macOS High Sierra, Apple’s Intelligent Tracking Prevention (ITP) feature has been the company’s response to rampant cross-site tracking by online advertisers, retail sites, and analytics outfits. Using a combination of cookie management, data anonymization, and some other features, ITP has always aimed to stop third parties from tracking you across multiple websites while still allowing the websites you’re actually using to work properly most of the time. Where many script blockers use domains to identify trackers and must be updated continuously, ITP attempts to operate algorithmically, identifying bad behavior and stopping it regardless of where it’s coming from.

Up until now, we haven’t had a ton of visibility into exactly what ITP is tracking and blocking beyond experiments we’ve run to confirm that it’s working in the first place. Safari 14’s new Privacy Report feature changes that, though as others have pointed out, it can lead you to slightly misleading conclusions.

As you load pages on different domains, ITP notes every third-party domain that each page attempts to contact. When the same third-party domain starts showing up multiple times across many pages on many domains, ITP determines that the site answering those requests is probably tracking you across websites, so ITP curtails the amount of information that the site can gather (this is what Apple means when it says that ITP works using on-device machine learning rather than checking with some centrally located list of trackers available online somewhere). By prompting the user using Apple’s Storage Access API, introduced in Mojave, third-party sites that actually need to work across multiple domains can request the permission to do so, but it doesn’t happen by default.

You can now see a list of all these domains in two places. When you’ve loaded a webpage, click the shield to the left of Safari’s address bar to view a list of all trackers that are active on that particular site. On the Start page, click the button below your favorites and recently visited sites to see a more holistic Privacy Report that stores information about the sites you’ve visited, the trackers Safari has encountered, and which trackers were used on which sites. Note that because of the way ITP works, these trackers aren’t being totally blocked; you’ll still show up as a pageview to a Google Analytics tracker when you visit a site that uses Google Analytics. But these trackers shouldn’t be able to determine what other sites you’ve visited, preventing them from painting as detailed a picture of your own unique browsing habits.

Unlike some past macOS and Safari updates, it doesn’t look like the core behavior of ITP has changed in the move from Catalina to Big Sur. Sometimes when you run newer versions of Safari in older macOS versions, you don’t get all of ITP’s latest protections, but it seems like Safari 14 running on Mojave and Catalina are behaving the same way and showing the same Privacy Report data as Safari 14 running on Big Sur.

Password monitoring

This feature’s name makes it sound vaguely ominous, but it’s just another feature meant to improve your password hygiene. If you’ve stored a password for a particular site in your Keychain, and that site happens to be involved in a data breach, Safari can flag it for you and help you change your password.

This is a pretty common feature in many password managers, and it’s not the first password-manager-esque feature that Apple has adopted to make passwords more secure for people who exclusively use Apple’s hardware and software. Safari 13 could warn you about weak passwords, and Safari 12 added a strong password generator and could warn you about reused passwords. If you ever want to step outside of Apple’s ecosystem, even if you just want to run a third-party browser on macOS, you’ll still need to use a password manager like 1Password, LastPass, or Bitwarden to gain the same capabilities and keep things synced between all your devices.

No more Flash

Safari dropped support for all non-Adobe Flash NPAPI plugins (think Java and Silverlight) back in Safari 12 and macOS Mojave, but Flash was allowed to stay on in a disabled-by-default capacity. Safari 14 removes Flash support entirely, regardless of whether it’s running on Mojave, Catalina, or Big Sur.

It has been around a decade since Steve Jobs announced Apple’s intent to abandon the then-popular Flash plugin on its mobile devices, presaging an industry-wide move away from Flash over the next few years. Apple is getting rid of Flash this year, but for what it’s worth, so is Adobe; the company has said it will stop providing security updates for the Flash player sometime this year (as of mid-October, they were still being released).

Translating pages

Translating a page in Safari 14.
Translating a page in Safari 14.

For users in the US and Canada, Safari now offers webpage translation to and from English, Spanish, Simplified Chinese, French, German, Russian, and Brazilian Portuguese. A small translation icon will show up on the right side of the title bar when you are on a page that can be translated; click it to choose a language to translate into, and click it again to translate it into a different language or revert to the original. This is something other browsers have offered for a while, but it’s nice to see Safari pick up support for it, even if it is still labeled “beta” for now.

WebP image support

For a list of every single Safari 14 addition, including HTTP/3 support, incremental loading of PDFs rather than all-at-once loading, and new JavaScript and CSS additions, you should just read the release notes. But one other feature is worth calling out, if only because Safari has been a longtime holdout among all the other browser makers: support for WebP images.

Google-developed image format, WebP promises to reduce both lossless (PNG) and lossy (JPEG) image sizes by 25 or 30 percent, saving bandwidth that can either be used to reduce total page size or improve image quality without increasing page size. Once people who design websites can assume widespread WebP image support, they can actually start using it. There’s also support for animated WebP files that can replace GIFs and can result in both higher quality and lower file size.

Here’s a microcosm of both the promise of and the problems with WebP: for every GIF I’ve generated for this review, I’ve generated a WebP file that looks better and takes up between one-half and one-fifth (!) the space. But I can’t actually use those files in this review, because the Ars CMS doesn’t support them, because before Safari 14 came out not all major browsers had adopted support for the format (no shade on the hardworking admins who keep Ars Technica running, either—this is the same calculation that most Web developers are going to make when trying to make their pages work properly for as many readers as possible).

Apple has also added rudimentary WebP image support to macOS itself—at least, you can view and edit static WebP images in the Finder, Quick Look, and Preview, while Catalina has no native support for the file format outside of Safari 14. You still can’t properly view animated WebP files outside of Safari, but it’s a step in the right direction.

Safari’s adoption of WebP support does not ensure the format’s widespread adoption or success. All efforts to replace widely used image formats like PNG, JPEG, and GIF have been halting start-and-stop affairs, hindered by the existence of multiple competing standards from multiple companies who are all hesitant to support each others’ technology lest they give up a competitive advantage. But as when Apple adopted HEIF and HEVC support back in High Sierra and iOS 11, the potential space savings are a tangible upside that’s worth pushing for in the long run, even when the new formats cause problems.

VP9 video codec and HDR support

While we’re on the topic of new formats, Safari 14 and iOS 14 both add support for Google’s VP9 video codec, which enables (among other things) playback of 4K YouTube videos. This is one of the few Safari 14 features that only appears to work on Big Sur, though. Try to view a 4K YouTube video in Safari 14 on Catalina, and you’ll see that the playback options still top out at 1080p. Other browsers, including Chrome, continue to offer 4K YouTube support on older macOS versions.

Safari 14 will also playback 4K HDR video, but only on 2018-and-later Macs with an Apple T2 chip inside. The T2 handles hardware video encoding and decoding on those Macs rather than the Intel or AMD GPU, and it supports 4K HDR video while older Macs that rely on their GPU for encoding and decoding do not.

Other apps: Messages

At long last, I can pester people with balloons from my Mac.
At long last, I can pester people with balloons from my Mac.

The old Messages app had removed any third-party messaging functions it once had, but it was still fundamentally the same app it had been since Apple overhauled and replaced iChat back in Mountain Lion.

The new app is a ground-up overhaul. It’s now a Catalyst app, which means that instead of merely aping the look of the iPad Messages app, it essentially is a windowed version of the iPad Messages app, give or take a handful of Mac-specific tweaks and multi-window support. This helps to rectify longstanding disparities between the two versions of the app—you’ll actually see balloons when someone sends them, instead of seeing “(sent with Balloons)” and using your imagination. You can send iMessage effects from your Mac now, too. Built-in integration with your Photos library, access to Memoji Stickers, and the quick GIF search features from iOS and iPadOS are all accessible when you click the App Store icon next to the text entry field.

The App Store icon implies that other apps will be able to extend the capabilities of the Messages app just as they can in iOS and iPadOS, and it’s possible that on Apple Silicon Macs, installing iOS apps with Messages Extensions included will make them show up alongside the built-in options automatically. But even without anything from third parties, the added functionality is long overdue in macOS.

As in iOS, the other main additions to the Messages app in macOS are things that other group chat apps like Slack and Discord have been doing for a while. Individual contacts and group messages can be pinned to the top of the app. Within group messages, you can now thread replies to individual messages and tag specific people if you want to get their attention. Group threads can have their own image added, either a picture from your Photos library or an emoji or Memoji with a colored background you choose. Pinned contacts and conversations will preview the last-received message before you click on it.

Finally, the Search field becomes more powerful and tries to be useful before you even type anything in. Recent photos, links, locations, and documents will all show up in the left-hand sidebar before you even type anything in, alongside a thumbnail for whichever person or group sent them.


The Photos app gets mostly minor upgrades in Big Sur, including a “vibrance” slider in the color options that can boost warm tones in photos without altering other colors, more music for Memories slideshows, and an option to adjust the intensity of photo filters. Apple says that the retouch tool has been improved using “machine learning,” which I always find vague and unsatisfying as an explanation for why something works better than it did before, but using it to touch up areas of photos did generally give me better results than editing the same photos in the same way in Catalina, with less visible blurring and fewer noticeable image artifacts (see a not particularly realistic but nevertheless illustrative example above).

The most significant addition is probably a range of actual color adjustments available when editing videos. Some photo-specific controls like redeye filters and the retouch tool are grayed out, but you can adjust exposure, color, white balance, contrast, and other settings just like you can with photos. The Trim tool, previously hidden behind a settings gear when viewing a video, is automatically pulled up when you go into edit mode on a video. Definitely handy for quick home movie edits.


The new Catalyst Maps app in Big Sur.
The new Catalyst Maps app in Big Sur.

Like the Messages app, the Maps app in Big Sur has been remade as a Catalyst app, which means it’s suddenly a lot more like the version of the app you see in iOS and iPadOS 14. Maps is not nearly as central to the Mac experience as the Messages app is, which if anything makes it a better candidate for a Catalyst conversion.

You can see our iOS 14 review for all the new features in the Maps app. But even though the apps are doing the same things, the Maps app isn’t just a clone of the iPad version; it has a persistent sidebar rather than one that slides in and out based on context, and things you click on the map (as in the screenshot above) show up in their own bubble rather than using the sidebar. If you’ve used the Find My app on the Mac, the Maps app will be familiar.


Mail is maybe the best example of a place where the new unified title bar and top-to-bottom-column design works pretty well.
Mail is maybe the best example of a place where the new unified title bar and top-to-bottom-column design works pretty well.

The actual capabilities of the Mail app, as best as I can tell, haven’t actually changed much in Big Sur. But it is worth pointing out that it’s one of the apps transformed the most by Big Sur’s new unified title bar style in a way that I think generally declutters the app and makes it function better. Buttons are now a uniform size and sit directly over the part of the window that they affect, and the way the title bar is formatted makes it clearer that the message and unread counts apply to the specific mailbox you’re looking at and not all mailboxes. Aforementioned contrast gripes aside, it’s a good example of what the new design can do well.


This app changes even less than Mail in the move from Catalina to Big Sur, since it was already using a fairly condensed title bar design in the first place. The biggest functional difference is that your calendar inbox now shows up in the sidebar, instead of as a bubble that floats over the rest of the app. Use the buttons above the sidebar to toggle back and forth between your inbox and the list of calendars.


I assigned her a reminder while minding the Finder.
I assigned her a reminder while minding the Finder.

Among the handful of minor enhancements the Big Sur reminders app picks up is the ability to assign reminders to people you share reminders with via iCloud. Once you’ve added other people to a list, you’re free to assign individual tasks to different people, where they’ll show up under a new “assigned to me” area in the sidebar. Siri will also suggest reminders using messages from the Mail app, sort of like the Calendars app has done for a while now.


Notes doesn’t benefit as much as Mail from the new top-to-bottom column design that aligns title bar buttons with the content that they affect, since the Notes app’s title bar in Catalina was already pretty condensed. The main changes to the app are the addition of standard bold/italic/underline/strikethrough toggles to the formatting menu and a new “top hits” list that separates your top search results from the chronologically arranged list of all the hits that come up when you do a search.

Time Machine switches to APFS

For as big a change as this seems to be, Time Machine’s long-awaited switch to APFS has been made with remarkably little fanfare—it shows up neither on Apple’s overview of Big Sur’s features, nor in any WWDC session. But in Big Sur, Time Machine does make the leap from using HFS+ to using APFS, and, at least in my limited testing, it does appear to have real-world speed benefits (and a couple of minor inconveniences that you may or may not run into).

In Catalina, you select an external volume connected via Thunderbolt or USB to use with Time Machine, and the partition is reformatted as an HFS+ volume; whether you encrypt it or not is up to you. Time Machine creates a Backups.backupdb folder on the drive, and inside of that folder is a bunch of other folders: one each for each Mac you’re backing up to that drive, and then within those, one for every discrete backup each Mac has made.

Each of those backup folders appears to contain a full collection of every single file on your disk at the time, though in reality files that didn’t change between backups are hard linked so that you’re not wasting tons of space storing the same file over and over. If there’s space left on the HFS+ volume that’s not being used by backups, you’re free to use it for other things.

That changes in Big Sur, at least when you set up a new Time Machine volume. According to The Eclectic Light Company’s Howard Oakley, who has taken it upon himself to describe Apple’s APFS changes in Big Sur in lieu of an official deep dive, Apple has added a new APFS volume role called “Backup” specifically for Time Machine backup volumes. Unless you’re backing up to a network drive or continuing to use an HFS+ Time Machine configuration that you set up in a previous version of macOS, Time Machine will only backup to one of these special APFS volumes. And once you’ve designated a disk as a Backup volume, you can’t do anything else with it. It’s used for Time Machine backups and nothing else, and you can’t back more than one Mac up to the same APFS volume (you get an error message if you try). That said, because of how APFS works, you can always use Disk Utility to create non-Backup APFS volumes in the same container to backup multiple Macs to the same drive or use the drive’s free space for other things.

Backups in Big Sur no longer take the form of endless nested folders, but of a series of APFS snapshots that each look like their own distinct volume. As with Time Machine in older versions of macOS, though, files that don’t change between backups are only actually stored once to save disk space.

If you have an HFS+ Time Machine disk already set up and you want to continue using it with a Big Sur Mac, Big Sur will still use existing HFS+ Time Machine volumes without changing anything. To get the benefits of the new APFS version of Time Machine, you’ll need to start fresh, since there doesn’t appear to be any kind of conversion option.

About networked backups

Time Machine has always worked just a bit differently when you’re backing up to a server, since, unlike with a local disk, macOS can’t really assume anything about the underlying filesystem of the drive you’re backing up to. In this case, Time Machine in Catalina uses a “sparsebundle” disk image to create a virtual HFS+ filesystem. This does two things: it gives Time Machine a “disk” it can work with, regardless of whether the server’s disks are formatted using ZFS or NTFS or APFS or whatever other filesystem you can think of. It means that the backup “disk” only takes up the amount of space it needs on the network drive (you can generally set up a quota on the server-end to limit the maximum size of the sparsebundle image).

That doesn’t really change much in Big Sur, except that the sparsebundle is now APFS-formatted, and, when you open it, it acts the same way a local backup disk does. Our speed testing also showed improvements over the old HFS+ version of Time Machine when using a networked volume, though it was admittedly more modest than when using a local disk.

Speed testing Time Machine

To do a bit of comparative speed testing, we used the same 2020 iMac booted into Catalina and the release candidate of Big Sur to backup to the same local disk and networked volume. To test performance with a local disk, we did an initial full system backup using around 180GB of data (the backups weren’t exactly the same size because they were backing up different versions of the operating system, but they were close enough that they wouldn’t invalidate our conclusions here). We then added another 25GB of data and performed a second backup. To test networked backup performance, we did one backup of a little over 200GB of data to the same server.

When you backup to a local disk in Big Sur on an Apple T2 Mac, encryption is not optional as it is in Catalina or on Big Sur running on a Mac without an Apple T2; it’s still optional either way if you back up to a networked target. We’re running all of these speed tests with encryption enabled to level the playing field, and these times do not include the lengthy upfront encryption process that is performed on the HFS+ volume when you set up an encrypted backup in Catalina. The local backups were done to a 1TB SSD connected via a 10Gbps USB connection. For the networked backups, both computers were connected to the same router via 1Gbps wired Ethernet connections, and the backups were stored on two 5400RPM 2TB internal SATA drives set up in a mirrored software RAID configuration.

Catalina 10.15.7 (HFS+)Big Sur 11.0.1 RC (APFS)
Local backup (initial) 44 minutes16 minutes
Local backup (follow-up) 8 minutes2 minutes
Network backup 1 hour 52 minutes1 hour 15 minutes

Across the board, Time Machine in Big Sur backing up to an APFS volume (or an APFS sparsebundle on a file server) was faster than Catalina backing up to the same hardware using HFS+. The benefits were more noticeable when using a local volume, though this may just come down to data transfer bottlenecks.

This was a fairly simple test, and it doesn’t necessarily reflect what you’ll see once you’ve got months of backups stored on a disk. But at least on the surface, this looks like a solid speed upgrade for Time Machine, and taking advantage of the features of a modern filesystem should hopefully make it more consistent and reliable, too.

macOS on Apple Silicon Macs

The Apple M1 is the first in what promises to be a long line of Apple-developed Mac processors.
The Apple M1 is the first in what promises to be a long line of Apple-developed Mac processors.

It’s hard to believe it has been 15 years since the last time the Mac switched processor architectures. But what in 2006 seemed like the most logical move—using the same x86 processors to build computers that everyone else did—in 2020 now feels like a liability, given Intel’s well-documented and continuing issues with its manufacturing technologyand AMD’s apparent struggles to meet demand for the first truly competitive laptop chips the company has shipped in at least a decade. Apple has never been particularly sentimental or preoccupied with maintaining backward compatibility in perpetuity, as Microsoft is with Windows. So if the processors aren’t good enough, and it doesn’t seem like they’ll be good enough any time soon, throw ‘em out.

Apple’s strategy for ensuring software continuity and a smooth transition relies on essentially the same methods that made the PowerPC-to-Intel transition possible. Apple is modernizing the macOS bootloader and using translation software to allow current x86-64 Mac apps to continue to run while developers develop ARM versions of their apps (or, more likely for a few years, Universal apps that will run on either architecture). The goal, once an Intel Mac and an Apple Silicon Mac are booted up next to each other, is to make them look the same way and do most of the same things despite the radically different underlying hardware.

We’ll try to stick to firmware and software features without diving too deep into the actual hardware architecture differences; these things are not Big Sur features as such, but since Big Sur will be the first macOS version to run on Apple Silicon Macs, a Big Sur review seems like the best place to document them. All of this will apply to the new MacBook Air, MacBook Pro, and Mac mini that Apple announced this week, and presumably all the other Apple Silicon Macs that follow

Booting and recovery

Intel Macs boot using an EFI-based bootloader that replaced the older Open Firmware used by PowerPC Macs—Apple was one of the first PC companies to begin using EFI, before it became more common in Windows PCs during the Windows 7 era. The bootloader provides pre-boot functionality to Macs, including choosing your boot target, booting from external or network sources, booting into Target Disk Mode or Recovery mode, resetting NVRAM, or booting into diagnostic mode.

Apple Silicon Macs have a bootloader more like the one iOS and iPadOS use, but it’s modified to allow some more traditional Mac features, like handling multiple macOS installs on one or more physical drives, booting multiple versions of macOS on the same computer, and supporting macOS Recovery. Any version of macOS signed by Apple will be able to run on these Macs; it’s not clear if other ARM-based operating systems like Linux or even Windows will be able to run on these machines. Apple does say that Apple Silicon Macs can boot from external volumes without changing the Mac’s security settings, unlike Apple T2 Macs—this is because these security settings can now be set per volume. You can boot your internal disk with all of Apple’s security protections intact and boot in a reduced-security mode from an external disk without needing to change anything.

The new bootloader will do a bunch of the same things that the Intel Mac bootloader does, but it’ll be a bit easier to use. Intel Macs use a bunch of different key combinations that you need to hold down at boot to do different things. Apple Silicon Macs simplify this. Now you just hold down the Mac’s power button (or TouchID button) to bring up a menu that lays out all the different boot options.

In addition, the recovery partition macOS has had since Lion is supplemented with another, apparently untouchable “System Recovery” volume. Stored in a separate APFS container, this volume can restore both macOS and the standard full-featured macOS recovery volume. It’s intended as a replacement for Intel Macs’ Internet Recovery feature, which can boot from an Internet-based recovery partition when your internal drive is totally hosed (or has been replaced). If System Recovery is unavailable or broken in some way, your last-ditch option is to connect your Mac to another Mac and use Apple Configurator to try to resuscitate it. This method is already used to restore Apple T2 Macs with busted firmware.

Goodbye Target Disk Mode, hello “Mac Sharing Mode”

If you boot up a PowerPC or Intel Mac while pressing the T key, the Mac would boot up into something called “Target Disk Mode.” You could then plug that Mac into another Mac with a FireWire, USB-C, or Thunderbolt cable (depending on the model you’ve got) and mount its internal drive as external storage. This was useful when you needed to move files from one Mac to another as quickly and easily as possible, or as a sort of diagnostic or file recovery mode if the Mac wouldn’t boot into macOS proper for some reason.

Apple Silicon Macs remove Target Disk Mode, replacing it with “Mac Sharing Mode.” This mode will mount the Mac’s internal drive and share it over a network using SMB. This is a less-than-ideal replacement for Target Disk Mode if you’re talking about speed, since even a Mac wired to a 1Gbps Ethernet connection won’t transfer data as quickly as one attached via a 20 or 40Gbps Thunderbolt 3 cable. But it could potentially be more convenient. And I imagine most Mac users don’t use Target Disk Mode often enough that it will come up too often.

The return of universal binaries

To ease the pain of app distribution, developers whose apps worked on both PowerPC and Intel Macs could distribute a “universal binary” containing all the code needed to run natively on either architecture. Back when macOS was making the jump from 32- to 64-bit apps, universal binaries could contain both 32- and 64-bit code. And now that Apple Silicon apps are here, universal binaries will be making a comeback.

To make it clear, here’s what will and will not run on different types of Macs while this transition progresses:

  • Intel-only apps will run on Intel Macs natively, and most will run on Apple Silicon Macs thanks to the Rosetta translation software (more on that momentarily).
  • Universal binaries with both Intel and ARM code will run on both Intel and Apple Silicon Macs natively. You can choose to run them via Rosetta on Apple Silicon Macs if you need to for some reason.
  • Apple Silicon-only apps will run on Apple Silicon Macs, but not Intel Macs. In these early days, the most common kind of app like this will be iOS and iPadOS apps, which will run directly on Apple Silicon Macs without modification but won’t run at all on Intel Macs unless they’ve been repackaged specifically for Macs using Catalyst.

It’s not really relevant, but according to Apple’s documentation, it is actually technically possible to make a five-way universal binary that includes 32-bit PowerPC code, 64-bit PowerPC code, 32-bit Intel code, 64-bit Intel code, and 64-bit ARM code. I can’t imagine why a developer would spend time on this, but it is impressive just how long this specific method of app packaging has been useful for Apple as it has navigated various architectural transitions.

Rosetta 2

The original Rosetta translation software eased the transition from PowerPC to Intel Macs by making sure that most apps written for PowerPC Macs would continue to run on Intel Macs, in case your app’s developer was behind the curve on creating an Intel version of their app or if you’d just paid a bunch of money for Microsoft Office or Adobe Photoshop and didn’t want to shell out again for a new Intel-native version. Today’s model of continuous, rapid development and software-as-a-service will doubtless make the Intel-to-ARM process go a bit more quickly for the apps that most people use, but in the meantime, Rosetta 2 is here to bridge the gap again.

But like the original version of Rosetta—which wouldn’t run the Classic macOS environment, software that required the G5 processor, System Preferences panes, and a handful of other odds-and-ends—there are a few things that Rosetta 2 won’t do. Rosetta 2 won’t translate kernel extensions, x86 virtualization software like Parallels or VMWare Fusion, or apps that use newer Intel instruction sets like AVX, AVX2, and AVX512. For apps that already know to check for AVX support, since those instruction sets aren’t available on all Macs that run Big Sur, the apps should see that the instructions aren’t supported and run without issue.

Aside from those limits, though, Rosetta 2 seems even more comprehensive and capable than the original version. Apple’s programming guidelines for the original Rosetta say specifically that the technology isn’t well-suited for apps with “intense computing needs,” including 3D games and modeling apps. But Apple specifically highlighted the performance of 3D apps when it demoed Apple Silicon Macs at WWDC, suggesting that the performance of most apps translated via Rosetta 2 won’t feel slow and bogged down, as heavier PowerPC apps sometimes could when they were running on early Intel Macs.

One thing that ought to make Intel apps feel a bit faster is that Rosetta 2 will recompile entire apps at once—this happens when you’re installing apps from the Mac App Store or via an install package or when apps are launched for the first time (presumably for apps that use the drag-to-Applications-to-install method). According to Apple, these translated apps will be “refreshed” when you install operating system updates, so you benefit from any bugfixes or performance improvements that Apple introduces. The old Rosetta had a cache that could be used to avoid translating the same bits of code over and over if you were doing the same thing multiple times within an app. But this cache didn’t persist between app launches, and it wasn’t done ahead of time.

Intel and ARM code can’t be mixed and matched; you can’t run an ARM app and use an x86_64 plugin, for example. When you need to use older plugins, a checkbox in a Universal app’s Get Info window will force the app to run using Rosetta rather than running natively. Apple’s documentation uses as an example of this, so presumably most apps in Big Sur running on Apple Silicon Macs will be Universal apps rather than ARM-only.

App developers can have their apps check to see whether they’re being run in Rosetta mode before trying to use those instruction sets, but it’s on the developer of the app to make sure that the app knows to check in the first place.

How long will Intel Macs stick around?

Notoriously averse to talking about its hardware or software roadmaps more than a few weeks in advance, Apple is playing a bit coy about how long Intel Mac owners can continue to expect software support. The WWDC presentation about Apple Silicon Macs said they could expect support for “years to come,” which implies more than one year but not much else.

Apple typically starts dropping Macs from their support list between six and eight years from when they were first introduced—Big Sur drops most 2012 Macs and a smattering of newer ones—so the absolute best case for owners of 2020 Intel Macs is new versions of macOS for another six or seven years. But people who bought PowerPC Macs in 2005 or 2006 as the Intel transition was happening got much less software support than that. Leopard, released in 2007, was the only new version of Mac OS X released after the Intel transition began that supported Intel and PowerPC Macs at the same time. Snow Leopard dropped PowerPC entirely in 2009, and Leopard (mostly) stopped getting security updates in mid-2012. So that’s six or seven years of software support, technically, though those Macs didn’t get any major new feature updates for most of those years.

I have no particular inside information, but I imagine that new macOS versions for Intel Macs will fall somewhere in between those two poles—a 2020 Apple Silicon Mac will almost certainly see a few more macOS releases than a 2020 Intel Mac, but I think Apple will give Intel Mac owners more than a couple new macOS versions before relegating them to security-updates-only status.

Some of that just reflects the fact that the modern Intel Mac is in a much better position than PowerPC Macs ever were. In fiscal year 2005, right as it was announcing the Intel transition but before it had begun, Apple sold a total of about 4.5 million Macs. On average, Apple has sold roughly that many Intel Macs per quarterevery quarter since 2011 or 2012. The universe of Intel Macs is so much bigger than the universe of PowerPC Macs ever was, and that’s way more people to leave out in the cold if you stop keeping their computers updated and patched prematurely. Here’s hoping that everyone out there with a recent-ish Intel Mac has at least four or five more versions of macOS to look forward to.

Security: Big Sur’s signed system volume

Since El Capitan introduced System Integrity Protection in 2015 to make a handful of important system folders read-only by default, Apple has been slowly restricting access to more of macOS’ system files in the name of improving security and preventing malware. In Catalina last year, the company took a really big step that would have been impossible (or, at least, much harder to implement) before the APFS filesystem: splitting the read-only system files and the user-accessible folders onto two totally separate volumes.

In Catalina, that read-only system volume could be mounted as a read-write volume and modified if you really wanted to do it, though it would reset to read-only every time you rebooted the system. Big Sur goes one step further, completely sealing the system volume and making it totally impossible to modify. This cryptographically signed system volume (or SSV) won’t even boot if macOS detects that the system files have been tampered with, and you have to go way out of your way to make changes to the system volume yourself.

To briefly recap the foundation that Catalina laid: your system and data volumes are part of something called a Volume Group. These are linked volumes in the same APFS container that are seen as a single volume by the Finder and most other apps, and they share the same FileVault encryption keys. Apple uses “firmlinks” for files and folders on each volume to make these two volumes look like one big unified disk in the Finder. When you open your Applications folder, for instance, all of the apps you’ve installed yourself are actually stored on your user data volume, and almost all of macOS’ built-in apps live on the read-only system volume. But because of firmlinks, all of these apps can live in one folder side by side, and everything looks like it’s in the same place just like it actually wasin older versions of macOS.

Big Sur adds SHA-256 cryptographic hashing that verifies that files on the system volume haven’t been changed or otherwise tampered with. In case you don’t know what any of those words mean, let’s break it down in brief.

SHA-256 and cryptographic hashing, explained

SHA-256 is an algorithm that can look at any data and spit out a 64-digit hexadecimal number. Feed the exact same data to the algorithm, and it will always return the same hexadecimal number (called a “hash value”) in response. This SHA-256 generator demonstrates how it works. The phrase “The quick brown fox jumps over the lazy dog.” (with a capital T in The and a period at the end) should always return a value of ef537f25c895bfa782526529a9b63d97aa631564d5d789c2b765448c8635fb6c. Copying and pasting every line of dialog from the movie Bee Movie returns a value of 347d0b60a44e2f2ee5f30b1b0e6ea33d2596085e2cd88d7264a22d268e51d11b. The hexadecimal number is the same length, regardless of how large the source data is.

The SHA-256 algorithm is useful for data verification because even the tiniest changes to the original data returns a dramatically different hashed value. Change the “T” in the “quick brown fox” example from uppercase to lowercase, and you get an entirely new hash value of 18e8d559417db8a93707c11b11bb90b56638049a5994006ed4b2705e4d86587f. Remove the period and you get d7a8fbb307d7809469ca9abcb0082e4f8d5651e46d3cdb762d02d0bf37c9e592. You can even hash your hashes—feeding the original “quick brown fox” hash into the SHA-256 generator returns a hash value of a3b3b479ab54238c8b91b8f9ac778d19799570eadeab3fd5042123ba8c220ed0. This makes it incredibly useful for verifying file integrity, since you won’t get hash values that match unless you feed exactly the same data into the algorithm in the first place. To protect sensitive data like passwords, some apps even add in extra data on purpose before computing the hash value, making it harder to reverse-engineer—that extra data is called “salt.”

This is what Big Sur is doing. When code is run from the system volume, macOS checks the data’s hash against an original hash that is stored in the volume’s metadata. Any change, however small, to the files on the system volume would change what that hashed value looks like. If the current hash and the original one don’t match, the code won’t run.

The recursive hashing example also explains how the system volume’s “seal” works. Every branch on the system volume’s metadata tree is hashed individually, and the hash of parent branches verifies all of the child branches (since, remember, even a tiny change in one branch would cascade up and change all the other hash values too). What Apple calls a “seal” is the hash of the “root node,” or the hash value that encompasses all the other hash values. This seal is verified at boot and when updates are installed—and if the verification fails, you need to reinstall macOS.

It’s still possible to make changes to the System volume and then to boot from it, but it’s even more difficult than it was before. Per this post on Eclectic Light Company, you need to boot into the Recovery partition, run csrutil authenticated-root disableto disable verification of the SSV, mount the system partition, make your changes, and then run sudo bless --folder /mountpath/System/Library/CoreServices --bootefi --create-snapshot to create a new snapshot of the system volume that can then be used for booting (albeit without SSV protections).

Happily, you can still make bootable backups of the SSV, as long as the backup software you’re using has been updated for Big Sur and knows to back up everything, including the seal itself and all the metadata that the seal needs to be verified properly. Carbon Copy Cloner is one backup app whose team is generally on top of things.

How Big Sur installs system updates

The way the system volume works now means macOS has changed the way it handles software updates, since the system volume can’t just be mounted and modified.

When it comes time to install a major macOS update, Big Sur loads up a separate snapshot of your system volume in the same APFS container as your system and data volumes (this volume is a persistent hidden volume called “Update,” and it is visible if you boot into Catalina on the same system).

Booted from an APFS snapshot in Big Sur.
Booted from an APFS snapshot in Big Sur.

That snapshot of your current Big Sur install is then patched with the new update files. A new snapshot is then created and sealed; when you reboot next, you’ll use the new updated snapshot, which will be sealed and verified just like the old one was. When you look at your Big Sur system volume in Disk Utility, it will even show you that you’re booted from an APFS snapshot.

This is more or less how iOS updates work, and that the update itself can happen mostly in the background while the system is currently booted and active should reduce the amount of downtime needed to install software updates in the first place. Apple notes that if anything goes wrong during the update process and if, as a result, the seal on the SSV doesn’t match the way it’s supposed to, the system can roll back to the prior APFS snapshot of the system volume without rendering the Mac unbootable.

Catalyst changes

Big Sur brings a number of tweaks for Catalyst, the technology that allows iOS and iPadOS developers to port their apps over to the Mac. A lot of this is behind-the-scenes developer stuff involving what buttons and drop-down menus can look like, and we won’t get into all of it here. Mostly, though, those changes are meant to address complaints that these Catalyst apps feel insufficiently Mac-like.

A typical Catalyst app is scaled down to roughly 77 percent of its normal size to make its finger-friendly controls fit in better on a platform with a more precise cursor. This is less work for developers, who don’t need to redesign their app around a Mac app’s typical buttons and controls, but it can result in fuzzier text and images than native Mac apps (particularly on non-Retina screens).

Now, developers can click a “Optimized for Mac” checkbox in Xcode that allows apps to run at 100 percent of their normal size, preserving visual quality while using a standard macOS font size and changing iOS-style buttons and sliders to Mac-style buttons and sliders. But that also means developers will need to put in more work to make apps look right, since changing these controls and scaling settings might break things about an iPad app’s layout.

Apple says that text-heavy and graphics-heavy apps in particular can benefit from running in “optimized for Mac” mode, and the company’s Swift Playgrounds app running on Big Sur will be Mac-optimized. The downside is that optimized-for-Mac apps can only run on Big Sur; none of these new Catalyst features is being backported to Catalina, which will only be able to run iPad-style Catalyst apps.

The long-term future for Catalyst apps is unclear right now, and it may depend a bit on how developers decide to handle Apple Silicon Macs. If developers (and users) seem mostly happy to use unmodified iOS and iPadOS apps on the Mac, then it’s not super likely that developers will put a lot of extra time into making Catalyst apps. And if Apple wants everyone to start using SwiftUI to make apps that function on all Apple’s platforms, then the mix of UIKit and AppKit that is Catalyst won’t be the best way to make or maintain a cross-platform app in the long run, either.

Grab bag

Every year, the new version of macOS adds things that are worth pointing out but don’t really merit or require a deep dive—Big Sur has a particularly large number of these kinds of things, since so much of the work that has gone into the operating system is focused on the new look and Apple Silicon support. Here are some of the odds and ends I noticed while testing Big Sur.

Battery preference pane

Mac laptops get a brand-new Battery preference pane that brings some iOS-style battery stats to the Mac and combines them with the settings from the old Energy Saver preference pane.

On desktop Macs without batteries, you’ll find the Energy Saver preferences right where you left them; these look no different than they did before. This is a bit like preference panes for optical drive settings (or, in older Macs, for drawing tablets) in that it changes dynamically based on the hardware actually connected to your Mac at the time.

On Macs that do have batteries, you now get Usage History graphs that chart out your energy usage over either the last 24 hours or the last 10 days, while the Battery and Power Adapter views show you the energy usage and timing settings that ought to look familiar from past versions of macOS, and the Schedule view shows the same automated sleep and wake options as the Schedule button in the old Energy Saver pane (and the current desktop Energy Saver pane).

General preference pane and the “font smoothing” toggle

Not much has changed here, except that the setting for when to prefer creating new tabs versus new windows when opening documents has migrated over from the old Dock preference pane. Now, you have the ability to disable window tinting independently of your accent color (which we already talked about).

Apple has also totally removed the font-smoothing checkbox from macOS after disabling subpixel antialiasing in Mojave. In Catalina, unchecking the font-smoothing box makes an infinitesimal difference in how heavy fonts look. Zoom in and you’ll notice that an identical number and arrangement of pixels are being used whether font smoothing is enabled or not, but the “smoothed” font will just look a bit darker, with less of a difference between the lightest and darkest pixel used to render any given letter.

In Big Sur, the operating system just enables font smoothing, with no option to turn it off. I doubt many people played with this setting, at least once subpixel rendering was removed, so you probably won’t miss it.

The startup chime is back

All Macs released after the late 2016 MacBook Pros came missing one feature that had been a mainstay of the Mac across multiple operating-system versions, processor architectures, and Apple CEOs: the startup chime. Macs going all the way back to the 1984 original made a distinctive one-tone beep when starting up, but starting in 2016, all new Macs booted silently instead.

This was tied to hardware and not any given version of macOS, so those of you with older Macs never lost the chime in the first place. But a Catalina update added the ability to re-enable the chime on newer Macs through a terminal command. In Big Sur all Mac users can enable or disable the chime using a checkbox in the Sound preference pane. Bong!

Progress bar for managing iDevices

Restoring iDevices in the Finder gets a progress bar so you can more easily see where you are in the process.
Restoring iDevices in the Finder gets a progress bar so you can more easily see where you are in the process.

Starting in Catalina with the removal of iTunes, all of iTunes’ old tools for managing iDevices moved out into the Finder. When doing a software update or restore or a device backup for an iPhone, iPad, or iPod, you’d just get an animated icon in the sidebar letting you know something was going on. Big Sur adds a progress bar to the bottom of the Finder window, giving you more insight into what’s happening. And the sidebar icon is still there for when you’ve navigated away from the iDevice’s window but still want a general idea of what’s going on. The only time the progress bar didn’t pop up in my testing is when I was restoring a local backup to a new phone.

No more AFP file sharing

Way back in 2013, Apple switched macOS’ default file sharing protocol from the venerable AFP (Apple Filing Protocol) to the more common SMB (Server Message Block) protocol. But AFP has stuck around in a deprecated, no-longer-improving form in the years since, working as a fallback option or a bridge to older versions of macOS with outdated SMB implementations.

Big Sur finally removes AFP support from the operating system entirely; you’ll no longer find it listed as an option in any of the file-sharing settings. File sharing is still handled exclusively from within the Sharing preference pane, and Big Sur’s SMB version—3.02, the second-from-newest version currently available—is the same as it was in Catalina.

No Network Utility

RIP in peace, Network Utility.
RIP in peace, Network Utility.

The Network Utility app in older macOS versions gives you a user interface for a handful of networking-related statistics and tools that are more advanced than what you get in the typical System Preferences, but Big Sur removes it. You can still launch the Network Utility from Spotlight, but instead of the app you get a message telling you that the tool is deprecated. For the netstat, ping, lookup, traceroute, whois, and finger commands that Network Utility used to handle, you’re directed to use the Terminal.

OpenGL and OpenCL are still here, even on Apple Silicon Macs

Both the OpenGL graphics API and the OpenCL compute API have been officially deprecated in macOS since Mojave, and neither API had actually been updated for many years before that. Apple would rather you use Metal for all that stuff, thank you.

Nevertheless, Big Sur keeps both APIs as they have been since roughly 2013; OpenGL at version 4.1, and OpenCL at version 1.2. They will apparently be supported even on Apple Silicon Macs, which means that legacy apps that still use these APIs and run in Big Sur (and don’t have problems being translated by Rosetta) will continue to work as they do in Catalina. Don’t count on these APIs to be present in the operating system forever, but Apple isn’t forcing the issue just yet.

Build numbers in Disk Utility

This change will be modestly useful for troubleshooting: When you’re looking at a bootable macOS volume in Disk Utility, the app now reports the exact build number of the operating system on the volume as well as the OS version. (For the uninitiated, this is also the number you see when you click the OS version number in About This Mac.) This is useful when you’re testing beta builds, which all have different build numbers despite reporting the same OS version. And Apple frequently releases “supplemental updates” and security updates that increment the macOS build without changing the OS version number.

DriverKit support for PCI Express and SCSI

Apple introduced DriverKit in Catalina as a way for third-party hardware makers to create device drivers that didn’t require the use of kernel extensions (or kexts). Apple’s reasoning is that kernel extensions have too much access to the rest of the system, including all kinds of kernel activities that don’t have anything to do with the peripheral you’re connecting, and poorly written ones can cause kernel panics that bring the whole system down. Kexts are still supported on Big Sur for now, but Apple’s plan is clearly to stop allowing third parties to access the OS kernel in some future release of macOS.

The initial version of DriverKit in Catalina covered a much narrower range of accessories than the old-school I/O Kit, including networking controllers, serial devices, USB devices, and Human Interface Devices (HIDs) like keyboards, mice, gamepads, and other things that let you control the computer. Apple says that because DriverKit has supported these kinds of devices for a while now, kexts that support those kinds of devices will no longer load “by default” in Big Sur. You can expect that pattern to continue: as kexts are replaced by DriverKit extensions (“dexts,” in Apple parlance), they will gradually be deprecated and disabled in future macOS versions.

Big Sur adds two new kinds of DriverKit drivers: PCIDriverKit, for PCI Express devices connected via internal PCIe slots or Thunderbolt 3; and SCSIControllerDriverKit, for SCSI storage drives like RAID controllers and Fibre Channel devices. Going deep on the implementation is a bit much for an OS review, but the session video from WWDC gets into the weeds a bit.

Encrypted DNS support

Both Big Sur and iOS/iPadOS 14 include support for encrypted DNS connections using either DNS over HTTPS or DNS over TLS.

Because of the widespread use of HTTPS on today’s Internet, Internet service providers and other network managers can’t actually see the exact URL or the content of the sites you’re visiting. But because the DNS traffic—what your computer needs to connect a request for “” to the correct server’s IP address—is not encrypted, middlemen can still see the names of sites you’re visiting. When that DNS traffic is encrypted, in theory, middlemen will only see the IP address you’re requesting.

There’s some debate as to whether encrypted DNS is actually worth it. Even with an encrypted DNS request, ISPs can still see the sites you’re visiting by looking at the Server Name Indication (SNI) used to establish an encrypted TLS connection. And as with VPN services, at the end of the day you still do end up needing to trust a third party with your DNS requests (in this case, whichever encrypted DNS service you’re using, rather than your ISP).

Regardless of whether you consider encrypted DNS to be genuinely useful or security theater, Apple’s support of it brings the company in line with MozillaGoogleMicrosoft, and others, all of which have committed to some level of support for encrypted DNS.

Self-reported app privacy practices

Starting on December 8, 2020, all new apps and app updates submitted to the App Store (including the Mac App Store) will require developers to self-report about what information their apps are collecting and how they’re using it in an effort to boost privacy. Apps will also need to report on the privacy practices of any third-party data collectors included with your app.

This feature isn’t live so we can’t really evaluate it. It’s definitely a good thing to normalize, though the fact that this data is self-reported may make it a bit less consistent or reliable than it would be if it were evaluated by Apple or some other third party instead.

Upgrade now, or wait?

Big Sur has had the strangest development timeline of any macOS release we’ve seen since Apple started releasing betas to the public back in the Mavericks and Yosemite days. A gap of a few weeks between the new iOS and macOS releases in the fall has become normal in the last couple of years, but Big Sur has been held back so long that the first version we’re getting is already version 11.0.1; a release candidate for version 11.0.0 was never released to developers or otherwise (though if I had to guess, I’d say that Apple’s newest Macs will ship with some 11.0.0 build we haven’t seen before). Whether that’s because of the continued impact of COVID-19 on software development, something related to Apple Silicon Macs, or some other stubborn bug, we’ve been waiting for Big Sur an abnormally long time.

That extra gestation time has given Apple plenty of time to fix bugs that cropped up during the beta process, and I’ll say that later betas of Big Sur have felt more or less as stable as Catalina does on the same hardware. Catalina made significantly more disruptive changes under the hood, with new app signing requirements, new security and permissions requirements, and the removal of 32-bit app support. Apps that ran on Mojave often needed changes to work properly on Catalina, but apps that run on Catalina should be mostly fine on Big Sur (some minor visual artifacts aside).

If you can wait until Big Sur 11.0.2 or 11.0.3 comes out, that’s still always the safest course of action for a system that you rely on every day; version 11.0.1 of the OS still hasn’t gotten the road testing that comes with a wide public release. Catalina will keep getting security updates, and your apps won’t stop working. But if you really want Big Sur’s new look on your computer right now, it generally shouldn’t break most things most of the time.


In a lot of ways, Big Sur is the kind of incrementalist macOS update that we’ve come to expect in the last few years. It’s a collection of tweaks and minor feature upgrades and under-the-hood enhancements that bumps the platform forward but doesn’t radically change it. It simply builds on the foundation laid by the last few releases of the operating system, something I talked about last year. Big Sur makes the Mac look and sound a lot different than it did before! But it’s still close enough to what you’re used to that you’ll use it for a few weeks or months and then it will just be what macOS looks like.

When you pair it with Apple’s first processor architecture transition in 15 years, it becomes easier to see Big Sur as a statement about where the Mac is headed (the long-awaited bump to version 11.0 drives this home, too, of course). A Big Sur Mac, especially one running on Apple Silicon, is another hop closer to being an iPad, both visually and functionally. Apple Silicon Macs will literally run unaltered iPad apps. I don’t think those will replace native Mac apps that already exist any time soon, but it’s easy to see how things could go that way.

But like I’ve been saying for a while now, it does seem like Apple is going farther out of its way than is strictly necessary to make sure that the Mac is still the Mac. That includes making sure that long-deprecated APIs like OpenGL and OpenCL continue to function on Apple Silicon Macs and making specific changes to the iOS bootloader to make sure that people can still boot and manage a bunch of different macOS versions on their system. The default security settings are a bit tighter than before, especially for the sealed system volume, but tinkerers still have the latitude to execute pretty much any code they want on their Macs. It feels like sort of a cop-out to end another review with “the Mac is still its own distinct thing within Apple’s product lineup,” but every time they move it closer to the iPad, it feels like it’s worth restating.

The Good

  • The bright, fresh visual style mostly looks pretty good.
  • The Control Center (and other changes to the upper-right section of the Menu Bar) are genuinely useful additions.
  • The Messages app finally catches up to its iOS/iPadOS counterpart, thanks to Catalyst.
  • The APFS version of Time Machine seems like an improvement, though we’ll need to wait to see what its long-term reliability is like.
  • Aside from the old AFP file-sharing protocol and the Network Utility, Big Sur doesn’t remove too many things or add many new security settings that will break apps. There may be some visual issues, but my experience has actually been that Apple breaks a lot fewer apps moving from Catalina to Big Sur than it did moving from Mojave to Catalina.

The Bad

  • A general reduction in contrast makes it harder to discern the difference between many buttons and controls at a glance.
  • If you want to fix any of these contrast issues in the Accessibility settings, it should be possible to increase contrast or reduce transparency in certain places without making it an all-or-nothing setting.
  • Some of the new buttons and icons are nice. Some of them are less nice.
  • Big Sur on Apple Silicon Macs will give up the ability to run Windows in a virtual machine or on a separate partition, though Intel Macs can still do both things.

The Ugly

  • As usual, Apple is just a year or two more aggressive about dropping support for old Macs than I think they really need to be.

All Rights Reserved for Andrew Cunningham

One Comment

  1. JohnIL

    Have not been impressed with Big Sur, I can definitely tell with my older eyes that the changes are not a positive for my eye sight. Too bad Apple thinks everyone is using a retina display. I think Big Sur looks really bad on my 1080p ViewSonic monitor. Wish I could double the height of the Menu bar. Many fonts by default are too small and look a bit fuzzy. Thanks Apple for removing Font smoothing option. But since Mojave Apple has basically ignored non retina screens. No good options, lower resolution, get stronger glasses or a retina monitor.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.