# MacOS Big Sur

macOS Big Sur (version 11) is the seventeenth major release of macOS, Apple'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.
Big Sur is the successor to macOS Catalina (macOS 10.15). The release of Big Sur was the first time the major version number of the operating system had been incremented since the Mac OS X Public Beta in 2000. After sixteen distinct versions of macOS 10 ("Mac OS X"), macOS Big Sur was presented as version 11 in 2020, and every subsequent version has also incremented the major version number, similarly to Classic Mac OS and to iOS and Apple's other current OSes.
For the first time since OS X Yosemite six years earlier, macOS Big Sur features a user interface redesign. It features new blurs to establish a visual hierarchy, along with making icons more square and UI elements more consistent. Other changes include a revamp of the Time Machine backup mechanism, the control center from iOS 7, among other things. 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 2001, from 10 to 11. The operating system is named after the coastal region of Big Sur in the Central Coast of California, continuing the naming trend of California locations that began with OS X Mavericks.
macOS Big Sur is the final version of macOS that supports Macs with Nvidia graphics cards, specifically the 15-inch dual graphics late 2013 and mid 2014 MacBook Pro models, as its successor, macOS Monterey, drops support for those models.

## Development history

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.
To maintain backwards compatibility, macOS Big Sur identified itself as 10.16 to legacy software and in the browser user agent.

## System requirements

Unlike macOS Catalina, which supported every standard configuration Mac that Mojave supported, Big Sur drops support for various Macs released in 2012 and early 2013. Big Sur runs on the following Macs:
* iMac (Mid 2014 or later)
* iMac Pro (2017)
* MacBook (Early 2015 or later)
* MacBook Air (Mid 2013 or later)
* MacBook Pro (Late 2013 or later)
* Mac Mini (Late 2014 or later)
* Mac Pro (Late 2013 or later)
* Developer Transition Kit (only up to Big Sur 11.3 beta 2)
By using patcher tools (such as OpenCore Legacy), macOS 11 Big Sur can be installed on earlier computers that are officially unsupported, such as the 2012 iMac and the 2012 MacBook Pro. Using these methods, it is possible to install macOS Big Sur on computers as old as a 2008 MacBook Pro and iMac and 2009 Mac Mini running smooth with non-metal graphics.

## Changes
### Design

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, a 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 square shapes like iOS and iPadOS apps, and are distinctly more round. 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.

### Interface
#### Control Center

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 the Control Center on iOS and iPadOS.

#### Notification Center

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.

### System
#### Support for Apple silicon

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.

#### Support for iOS and iPadOS applications

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 overhaul

Time Machine, the backup mechanism introduced back in Mac OS X 10.5 Leopard, has been overhauled to utilize the APFS file system (introduced in MacOS High Sierra) instead of the outdated 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

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.

#### Signed system volume

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

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.

#### Encryption

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.

### Other changes

* Bilingual dictionaries in French–German, Indonesian–English, Japanese–Simplified Chinese and Polish–English
* Better predictive input for Chinese and Japanese users
* New fonts for Indian users
* The "Now Playing" widget has been moved from the Notification Center to the Menu Bar
* Podcasts "Listen Now" feature
* FaceTime sign language prominence
* Network Utility has been replaced with a message that it has been deprecated
* A new startup chime was added (it was absent on all machines released from 2016 to 2020) and is now enabled by default; an option was added in System Preferences to enable or disable this functionality.

## Application features
### Safari

Big Sur includes Safari 14, which was also released for macOS Catalina and macOS Mojave on September 16, 2020. Safari 14 includes features such as a new home page in which users can customize what features are visible in addition to being able to set a custom wallpaper. It also allows the viewer to preview a page and favicon before visiting it.
Safari 14 also includes built-in web page translations in English, Spanish, German, French, Russian, Chinese and Portuguese as well as support for 4K HDR content from Netflix on Macs with an Apple T2 chip, although none of these were made available for macOS Catalina and Mojave.
Privacy features such as iCloud Keychain (which notifies users of compromised passwords), extension privacy management and Privacy Report (which monitors privacy trackers and further increases Safari's security) were added for Safari 14. Users were now also able to import password from Google's Chrome browser in addition to being notified of compromised passwords.
Safari 14 also supports WebExtensions API, the WebP image format as well as VP9 decoding, the latter of which allows for the playback of 4K and HDR content from YouTube. In addition, it allowed for better performance and power efficiency.
Safari 14 ended support for Adobe Flash Player in September, three months prior to its end-of-life on December 31, 2020.

### Messages

The Messages app was rewritten to be based upon Apple's Catalyst technology to enable it to have feature parity with its iOS counterpart. The new version of the app included a refined design as well as the ability to pin up to nine conversations that can sync across iOS, iPadOS and macOS. Users were also now allowed to search for messages and share their names and photos. Photo thumbnails could now also be used for group chats on the app.
In addition, users could mention contacts by putting the @ symbol in front of their name. They were also able to reply to specific messages. Memojis, 3d avatars were also made available on Messages. On Messages, users could now select photos based on parameters.
In India, text message effects were added when users sent certain texts (e.g., texting "Happy Holi" will result in users seeing effects).

### Changes to the Mac App Store

Refinements and new features of the Mac App Store include:
* A new "nutrition label" section dedicated to the data and information an app collects, also featured in the iOS App Store
* A new extensions category for Safari
* Third party Notification Center widgets, similar to those also added in iOS and iPadOS 14.
* The ability to share in-app purchases and subscriptions on the Mac via iCloud Family Sharing