|A version of the macOS operating system|
|Source model||Closed, with open source components|
|November 12, 2020|
|Latest release||11.6 (20G165) (September 13, 2021 )|
|Update method||Software Update|
|Kernel type||Hybrid (XNU)|
|License||Proprietary software with open-source components|
|Preceded by||macOS Catalina|
|Succeeded by||macOS Monterey|
|Part of a series on|
macOS Big Sur (version 11) is the 17th and current major release of macOS, Apple Inc.'s operating system for Macintosh computers. It was announced at Apple's Worldwide Developers Conference (WWDC) on June 22, 2020, and was released to the public on November 12, 2020.
Most notably, macOS Big Sur features a user interface redesign that features new blurs to establish a visual hierarchy and also includes a revamp of the Time Machine backup mechanism, among other changes. It is also the first macOS version to support Macs with ARM-based processors. To mark the transition, the operating system's major version number was incremented, for the first time since 2000, from 10 to 11. The operating system is named after the coastal region of Big Sur in the Central Coast of California.
Providing some indication as to how the pre-release operating system may have been viewed internally at Apple during its development cycle, documentation accompanying the initial beta release of macOS Big Sur referred to its version as "10.16", and when upgrading from prior versions of macOS using the Software Update mechanism to early beta releases, the version referred to was "10.16". An exception to this was the Developer Transition Kit, which always reported the system version as "11.0". macOS Big Sur started reporting the system version as "11.0" on all Macs as of the third beta release.
Unlike macOS Catalina, which supported every standard configuration Mac that Mojave supported, Big Sur drops support for various Macs released in 2012 and 2013. Big Sur runs on the following Macs:
macOS Big Sur refreshes the design of the user interface, described by Apple as the biggest change since the introduction of Mac OS X. Its changes include translucency in various places, and new abstract wallpaper for the first time and a new color palette. All standard apps, as well as the Dock and the Menu Bar, are redesigned and streamlined, and their icons now have rounded-square shapes like iOS and iPadOS apps. Compared to iOS, Big Sur's icons include more shading and highlights to give a three-dimensional appearance. Its aesthetic has been described as "neumorphism", a portmanteau of new and skeuomorphism. System sounds are redone as well.
The new OS also brings further integration with Apple's SF Symbols, enabling easier use by third-party developers as UI elements for their applications through AppKit, SwiftUI, and Catalyst, which makes it possible to unify third party applications with the existing Apple-made design language.
An interface with quick toggles for Wi-Fi, Bluetooth, screen brightness and system volume has been added to the menu bar. This interface is functionally and visually similar to Control Center on iOS and iPadOS.
The Notification Center is redesigned, featuring interactive notifications and a transparent user interface. Notification Center also features a new widget system similar to that in iOS 14, displaying more information with more customization than previously available.
macOS Big Sur is the first release of macOS for Macs powered by Apple-designed ARM64-based processors, a key part of the transition from Intel x86-64-based processors. The chip mentioned in demo videos, and used in the Developer Transition Kit, is the A12Z Bionic. On November 10, 2020, Apple announced the first Mac Apple silicon chip, the Apple M1, in the Late 2020 Mac Mini, MacBook Air, and MacBook Pro. Apple has said that it will support Intel Macs "for years to come", and most software that has not been ported to run on ARM Macs can use Rosetta 2, an update of a compatibility mechanism originally developed for the PowerPC-to-Intel x86 transition. Likewise, Apple also introduced an updated universal binary format, Universal 2, which allows developers to package their applications so that they can run natively on both ARM64 and x86-64 processors.
On Macs based on Apple silicon, macOS Big Sur can run iOS and iPadOS applications natively and without any modifications needed from developers, aside from allowing the app to be available on the Mac App Store. The first Macs with this capability are those that use the Apple M1 SoC (system on a chip).
Time Machine, the backup mechanism introduced in Mac OS X 10.5 Leopard, has been overhauled to utilize the APFS file system instead of HFS+. Specifically, the new version of Time Machine makes use of APFS's snapshot technology. According to Apple, this enables "faster, more compact, and more reliable backups" than were possible previously with HFS+-formatted backup destinations. An independent evaluation of this claim found that Time Machine on macOS 11 in conjunction with APFS was 2.75-fold faster upon initial local backup and 4-fold faster upon subsequent backups relative to macOS 10.15's Time Machine implementation using HFS+. A more modest yet nevertheless significant advantage was noted as well for backups to network-attached disks.
New local (i.e. USB- or Thunderbolt-connected) and network-connected Time Machine backup destinations are formatted as APFS by default, though Time Machine can continue backing up to existing HFS+ backup volumes. There is no option to convert existing, HFS+-based backups to APFS; instead, users who want to benefit from the advantages of the new, APFS-based implementation of Time Machine need to start with a fresh volume.
In the new version of Time Machine, encryption appears to be required (instead of merely optional) for local disks, but it remains elective for networked volumes.
It is no longer possible to restore the whole system using a Time Machine backup, as the signed system volume is not backed up. Non-core applications and user data can be restored in full using Migration Assistant, preceded by a system reinstall if necessary.
Spotlight, the file system indexing-and-search mechanism introduced in Mac OS X 10.4 Tiger, is faster and the interface has been refined. Spotlight is now the default search mechanism in Safari, Pages, and Keynote.
The system volume containing the core operating system is cryptographically signed. Apple indicates this is a security measure to prevent malicious tampering. This includes adding an SHA-256 hash for every file on the system volume, preventing changes from third-party entities and the end user.
Software updates can begin in the background before a restart, thus requiring less downtime to complete. Because system files are cryptographically signed, the update software can rely on them being in precise locations, thus permitting them to be effectively updated in place.
macOS Big Sur supports encryption at the file level. Earlier versions of macOS (10.15 Catalina and older) supported encryption only at the level of entire volumes. As of June 2020, this capability is known to be compatible with Macs based on Apple silicon; it is unclear whether it is compatible with Intel-based Macs.
The Messages app was rewritten to be based upon Apple's Catalyst technology. This enables the app to have feature parity with its iOS counterpart. Alongside a refined design, the new Messages app brings:
Refinements and new features of the Mac App Store include:
The rollout of Big Sur came with several problems. Upgrading to the initial public release of Big Sur (version 11.0.1) bricked some computers, rendering them unusable. Many of these were 2013 and 2014 MacBook Pros, though problems were also observed on a 2019 MacBook Pro and an iMac from the same year. The initial rollout also disrupted Apple's app notarization process, causing slowdowns even on devices not running Big Sur. Users also reported that the update was slow or even might fail to install. macOS Catalina and Big Sur apps were taking a long time to load because of Gatekeeper issues.
The ongoing issues with the COVID-19 pandemic meant it was hard for users to visit an Apple Store to get their machines fixed. Shortly afterwards, Apple released a series of steps explaining how these Macs could be recovered.
Certain Apple applications running on early versions of Big Sur were reported to bypass firewalls, raising privacy and security concerns. This was addressed with the release of macOS Big Sur 11.2, which removed the whitelist for built-in programs. Conversely, security experts have reported that Big Sur will check an application's certificate every time it is run, degrading system performance. There have been reports that the operating system sends a hash back to Apple of every program run and when it was executed. Apple responded that the process is part of efforts to protect users from malware embedded in applications downloaded outside of the Mac App Store.
Some users have reported problems connecting external displays to Macs running Big Sur 11.1 and 11.2. 
In 2021, there were reports of two malware codes that infected macOS and include both x86-64 and ARM64 code. The first one was detected in early 2021. The second one, Silver Sparrow, was detected on nearly 30,000 Macs in February 2021.
The public release of macOS 11 Big Sur began with 11.0.1 for Intel Macs. Version 11.0 was preinstalled on Apple silicon Macs, and Apple advised those with that version to be updated to 11.0.1.
|Previous release||Current release||Current developer release|
|Version||Build||Date||Darwin version||Release notes||Notes|
|11.0||20A2411||November 17, 2020||20.1.0
|N/A||Preinstalled on MacBook Air (M1, 2020), MacBook Pro (13-inch, M1, 2020), and Mac mini (M1, 2020)|
|11.0.1||20B29||November 12, 2020||20.1.0
|Security content||Initial public release|
|20B50||November 19, 2020||Available for all Macs except Late 2013 and Mid 2014 13" MacBook Pros|
|11.1||20C69||December 14, 2020||20.2.0
|11.2||20D64||February 1, 2021||20.3.0
|11.2.1||20D74||February 9, 2021||Security content|
|20D75||February 15, 2021||Fixes bug where installation with insufficient free space could cause data loss - exclusive to the full installer|
|11.2.2||20D80||February 25, 2021||N/A|
|11.2.3||20D91||March 8, 2021||Security content|
|11.3||20E232||April 26, 2021||20.4.0
|11.3.1||20E241||May 3, 2021||20.4.0
|11.4||20F71||May 24, 2021||20.5.0
|11.5||20G71||July 21, 2021||20.6.0
Wed Jun 23 00:26:31 PDT 2021
|11.5.1||20G80||July 26, 2021||Release notes|
|11.5.2||20G95||August 11, 2021||Release notes|
|11.6||20G165||September 13, 2021||20.6.0
Mon Aug 30 06:12:21 PDT 2021