MacOS

macOS (formerly Mac OS X and OS X) is the operating system used on Apple's line of Mac computers since 2001. It is currently released for the Intel 64-bit (x86_64) and Apple Silicon (ARM64) architectures, and was previously released for Intel 32-bit (IA-32) and PowerPC.

macOS is the successor to both Mac OS Classic and NeXTSTEP, following Apple's 1996 acquisition of Steve Jobs's NeXT Computer, Inc., and various failed projects intending to modernize the aging Mac OS.

iOS and its derivatives were initially derived from macOS. macOS, iOS, and iOS-derived operating systems share a significant number of components.

Rhapsody and Mac OS X Server 1.0
The first attempt to turn OPENSTEP into a replacement for Mac OS was codenamed Rhapsody. Seeing the progress Microsoft had made with Windows NT, bringing stability, security, multi-platform portability, and native networking to the Windows operating system, Apple set out to bring these features to Mac OS. After the management failure of the Copland project, Apple CEO Gil Amelio proposed to instead acquire an established competing operating system with the desired qualities. This led to the acquisition of NeXT.

After two developer releases, Apple recognized that the Rhapsody operating system strategy was not going to be successful. As Amelio was ousted as CEO in 1997, with Steve Jobs becoming his de-facto replacement, the Rhapsody project grew quiet. It was released as the short-lived Mac OS X Server 1.0, and was also forked to become the Darwin operating system, later released as Mac OS X 10.0. While the Rhapsody project appears to have been a failure, it is still notable for being the testing ground for features critical to the success of Mac OS X, such as the Classic environment (codenamed Blue Box), allowing existing Mac OS applications to run on the entirely different Unix-based operating system, and the OPENSTEP API (codenamed Yellow Box), which became the Mac's primary user interface framework, Cocoa.

Rhapsody and Mac OS X Server 1.0 did not include any of Mac OS X's iconic features, such as the Aqua desktop interface, Quartz rendering engine, the Dock, or the Finder. Instead, it presents itself as merely an updated version of NeXTSTEP in Mac OS's Platinum theme.

Notably, Rhapsody supports Intel 32-bit processors. This was intended to allow Apple to license Mac OS to PC manufacturers such as Dell to directly compete alongside Windows, however, Apple was not able to reach agreements with these manufacturers. Support for Intel processors was initially dropped from Mac OS X, but with the later transition from PowerPC to Intel processors, Jobs admitted that Apple had continued to build and test Mac OS X for Intel since 2000.

Mac OS X Public Beta (Kodiak)
Apple's slow road of migration from the aging classic Mac OS to an operating system competitive with Windows NT (now in its fifth release as Windows 2000) led to significant customer, developer, and investor distrust of Apple's future - all of which the company needed to retain to ensure Mac OS X's success. To regain control of the story, Apple released the Mac OS X Public Beta on 2000. The beta, sold to the public for US$29.95, introduced the Aqua user interface, including the new Quartz rendering engine, the Dock, a port of the Finder, and new application icons. It received only two releases, one being for the US market, and the other being for the international market.

Mac OS X Public Beta is timebombed, refusing to boot into the GUI on 2001 or later. Purchasers of the beta were eligible to receive a $30.00 discount towards purchasing Cheetah.

Early public releases
Mac OS X 10.0 Cheetah was released on 2001, finally providing a true replacement to classic Mac OS. While labelled as stable, Cheetah was seen as a rough release by reviewers. It introduced Mail and TextEdit, while providing ported versions of classic Mac OS apps such as Sherlock. iTunes 1.1 was also included - its first release for Mac OS X.

Mac OS X 10.1 Puma quickly replaced Cheetah, releasing on 2001 as a free upgrade to existing customers. It included many the features considered to be missing from Cheetah, such as DVD Player and Image Capture. The general operating system performance was significant improved.

Mac OS X 10.2 Jaguar continued to rapidly improve the operating system. Releasing on 2002 at US$129, Jaguar was the first to use its codename in public marketing materials, going as far as to render its box art "X" logo in jaguar fur. It introduced features such as the Quartz Extreme GPU-based compositor, support for MPEG-4, Bonjour, iChat, Inkwell, Sherlock 3, and the CUPS printing system.

Mac OS X 10.3 Panther was released on 2003 at US$129. It introduced further Quartz-based features such as the Exposé window switcher, in addition to the XQuartz windowing system, enabling existing X Window System applications to run on Mac OS X, albeit with poor integration with the Aqua user interface. It introduced the Safari web browser as a replacement to Internet Explorer for Mac, iChat AV with support for IP-based audio and video conferencing, an initial version of FileVault, and support for Active Directory.

Intel era
Mac OS X 10.4 Tiger saw the first public release of Mac OS X for Intel processors. Initially released for existing PowerPC Macs on 2005 at US$129.95, it additionally went through a process of being tested on the Developer Transition Kit (2005), before being released with the first retail Intel Macs as 10.4.4 on 2006. It introduced Spotlight search, replacing Sherlock, unique for being dramatically faster and yet simpler than Microsoft's attempts at building a search engine into Windows, such as WinFS. System bootup processes, and other background processes started and stopped as part of using the operating system, became the responsibility of a new daemon, named launchd. It additionally introduced Automator, Grapher, Dictionary, Dashboard, VoiceOver, and integration with Apple's .Mac cloud service.

A stripped-down version of Tiger was used as the basis of the Apple TV (1st generation) operating system. Subsequent Apple TVs are based on iOS, and later tvOS. The Classic environment was not ported to Intel.

Mac OS X 10.5 Leopard was the final major release to support PowerPC-based Macs. Released on 2007 for US$129, it brought a refined version of the Aqua user interface, removing all use of brushed metal textures, and introducing 3D effects such as the transparent menu bar and Dock. It brought an improved Finder design based on the interface of iTunes at the time, including its sidebar design and Cover Flow feature. It introduced Objective-C 2.0, and with it, support for 64-bit Cocoa apps. It additionally introduced the Time Machine backup feature, and further integrated with MobileMe (formerly .Mac). The sandbox technology, fundamental to iOS, originated in this release, in addition to the system firewall. The Classic environment was removed in this release.

Leopard was the first release to be certified as fully UNIX 03 compliant, ending a lengthy legal dispute between The Open Group and Apple regarding unlicensed use of the UNIX brand name in Mac OS X marketing materials. While Leopard was intended to begin a transition to the ZFS file system, its ZFS driver only supported read-only access.

Mac OS X 10.6 Snow Leopard was released on 2009 for the new significantly lower price of US$29. It is remembered by its marketing tagline of having "no new features" - this marketing strategy going as far as the name appearing to simply be a minor improvement on Leopard. Rather than focusing on adding completely new functionality, existing features of the operating system received performance, design, and minor functionality improvements. It debuted new versions of apps such as Finder and QuickTime, rewritten to take full advantage of Cocoa rather than being a Carbon port of their classic Mac OS versions. Later, version 10.6.6 introduced the Mac App Store, which would be used to distribute Lion as a digital release. The ZFS feature from the prior release was removed due to licensing issues. A 64-bit version of the kernel first appeared in this release, although not enabled by default on most Macs.

It was the final release to be distributed on physical DVD media, and additionally the final release to support the initial generation of Intel Macs, which used 32-bit Intel "Yonah" processors. It was the final release to include the Rosetta PowerPC emulator.

"Back to the Mac" era
Mac OS X 10.7 Lion, also referred to as OS X Lion, brought design cues and features from iOS across to the Mac, among other features. It was released through the Mac App Store on 2011 for US$29.99, later releasing on physical USB media on 2011 for US$69.99. It introduced support for emoji, push notifications, AirDrop, FaceTime, Launchpad, and automatic saving of documents being edited. It introduced the simplified, iOS-like scroll bar. A beta of Messages (a rebrand of iChat centered around support for iMessage) was later released for Lion users. To avoid the need for a DVD release of the operating system, new Macs received Internet Recovery, which downloads a minimal version of the operating system to allow for maintenance and reinstallation of Mac OS X. It is the first release to support high-resolution Retina assets for the release of the first MacBook Pro with Retina Display, albeit not Apple's first attempt at supporting high-DPI displays in Mac OS X. iCloud superseded MobileMe with its introduction in 10.7.2.

OS X 10.8 Mountain Lion, officially dropping the "Mac" prefix of the operating system name, released on 2012 for a further reduced price of US$19.99. It was the first release of OS X developed and released under new CEO Tim Cook and overseen by new Senior Vice President of Software Engineering Craig Federighi. It introduced further features inspired by iOS, including the Notification Center, Notes, Messages (a rebrand of iChat with iMessage support), Game Center, Reminders, a redesigned Contacts (rebranded from Address Book), and a redesigned Calendar (rebranded from iCal). Mountain Lion introduced the Gatekeeper app security verification feature. It additionally included the ability to mirror a Mac display to an Apple TV via AirPlay (supported on 2011 and later Macs).

Mountain Lion switches to using a fully 64-bit kernel, removing support for 32-bit kernel extensions, and also therefore support for earlier Macs that used a 32-bit EFI implementation.

Yearly iteration and free upgrades
OS X 10.9 Mavericks was released on 2013 as the first major upgrade made available free of charge. With this release, the codenames switched from big cats to landmarks in Apple's home state of California. The operating system design was refined to remove many busy real-life "skeuomorphic" designs, in line with the philosophy of that year's iOS 7 redesign. AirPlay display mirroring was extended to allow an Apple TV to act as an extended desktop display. The iCloud Keychain feature was introduced, and the iOS Books and Maps apps were brought across to the Mac.

OS X 10.10 Yosemite brought the most significant redesign of the operating system to date. Released on 2014, it further reduces heavy design elements, such as dark gradients, three-dimensional renders, and realistic imagery, in favor of using simplified designs. These designs replaced many elements with a softer gradient or solid color, and introduced blur "materials" to signify depth, akin to the iOS 7 redesign it mimics. For the first time, Yosemite offers the option to display the Dock and menu bar in a dark theme, making these elements less distracting. Yosemite is unique in being the only release to use Helvetica Neue as the system font.

Yosemite introduced the initial version of Handoff, allowing tasks to be shifted between a Mac and an iPhone/iPad on the same iCloud account. Widgets were introduced to the Notification Center, and iPhoto was replaced with the iCloud-integrated Photos in 10.10.3. Spotlight was redesigned and improved to include Quick Look previews of search results, and to query information from the internet.

OS X 10.11 El Capitan was released on 2015. Light on features compared to its predecessor, El Capitan was akin to Snow Leopard in being a release bringing few new customer-facing features. It switches the UI font to the Apple-designed San Francisco. It introduced System Integrity Protection (codenamed "rootless", not to be confused with rootless in jailbreaking), protecting core operating system security from even the highest-privilege root user. It also introduces extensions, allowing apps to provide functionality to system features, such as to add a social media service to the Share menu, while remaining fully sandboxed from other applications. The Metal graphics API makes its first appearance on the Mac in this release.

macOS 10.12 Sierra rebrands the operating system once again, bringing the name into consistency with Apple's growing list of operating systems derived from iOS. Released on 2016, it carried the Siri assistant feature across from iOS, introduced iCloud Drive, added the ability for a Mac to be unlocked by the user's Apple Watch being in proximity, and introduced the Continuity Universal Clipboard feature. Tabbed window interfaces became a native feature of Cocoa, allowing multi-window apps to receive support for tabs instantly upon use on the new operating system, in addition to picture-in-picture video playback. Notably, it provided an early preview of APFS.

macOS 10.13 High Sierra again presented as a more incremental update. Released on 2017, High Sierra automatically migrates SSD-based Macs to the new, completed version of APFS, resolving numerous flaws with the long-standing Mac OS Extended (HFS+). It also includes Metal 2, an expanded successor to the initial Metal release in El Capitan, with the window server now rebuilt to be based on the new graphics API for better performance. As a result, some older Macs with GPUs not targeted by Metal were discontinued with this release. In 10.13.4, the system began to present a warning upon launching a 32-bit application, warning that it will cease to work on future releases of macOS.

macOS 10.14 Mojave was released on 2018, and began to present a shift towards removing old, disused functionality in the operating system. It removed built-in integration with popular social media websites, and while not removed, it saw the deprecation of OpenGL/OpenCL in favor of Metal. The APFS migration continued with Mojave, now migrating mechanical hard drives and Fusion Drives to the new filesystem. The remaining use case not supported by APFS is Time Machine backup drives. It introduced an early preview of Catalyst, with the iOS Home, News, Stocks, and Voice Memos apps ported to macOS as a demonstration of the technology. Perhaps most noticeably, it introduced a system-wide dark mode, theming entire apps with light elements on a dark background, rather than vice versa.

macOS 10.15 Catalina was released on 2019, adding numerous security features. A key highlight for developers is the initial release of Catalyst for public use, allowing iPad apps to be ported to run on macOS. DriverKit was introduced as the successor to kernel extensions, with DriverKit drivers executing as userspace programs, rather than running inside the kernel. Gatekeeper was improved to now require programs released after a cutoff date to be uploaded to Apple's notarization database. The Activation Lock feature from iOS was brought to Macs based on the T2 chip. Most impactful of all features introduced in this release, Catalina entirely removed support for 32-bit Intel programs as had been previously communicated, and replaced the aging iTunes with separate Music, Podcasts, and TV apps, with support for syncing iOS devices and iPods moved into Finder. The Sidecar continuity feature allows nearby iPads logged into the same iCloud account to be used as an external display to a Mac. A significant number of APIs became restricted in this release, requiring the user to consent to reading personal files, calendars, contacts, mail, and some sensitive operating system files, in addition to using Apple Events to interact with other apps. The operating system's own files were moved to a dedicated APFS volume, which is mounted read-only, as has always been the case in iOS.

Apple Silicon era
macOS 11 Big Sur (initially version 10.16 in early betas) brought another redesign to the macOS interface, and returned the operating system to being released on multiple architectures, supporting both Intel 64-bit and the newly-branded Apple Silicon line of ARM64 processors. Released on 2020, it finally increments the Mac OS X family's version numbers beyond the tenth major version, in line with the versioning scheme of Apple's other platforms. During the beta period, until 11.3 beta 2, the Developer Transition Kit (2020) was supported as a platform for developers to begin migrating their software to the new ARM-based platform. Apps not yet migrated to the new platform are supported through the Rosetta 2 translator for Intel 64-bit binaries. The operating system received a redesign in some aspects, predominantly through a refined menu bar design with a new control center menu. App icons were redesigned from freeform shapes to rounded square shapes akin to iOS app icons, in some cases with three-dimensional elements protruding outside of the shape. It introduces the extensive SF Symbols iconography library to the operating system. The iChat-derived Messages app was discontinued, replaced with a Catalyst port of the iPad Messages app. Time Machine was rebuilt to be based on APFS, specifically its snapshots feature, rather than using HFS+ hard links. The operating system volume is now cryptographically signed by Sealed System Volume. It was also the first macOS release to include the new SwiftUI, intended as a replacement for Apple's existing UI frameworks.

macOS 12 Monterey was released on 2021, introducing Shortcuts and TestFlight to the Mac platform, additionally bringing across privacy indicators, portrait mode for video and noise cancellation for audio, and SharePlay from iOS. It also introduced an AirPlay server, allowing other Mac and iOS devices to use a Mac as a remote display. It introdues the machine learning-based Live Text and Visual Look Up features.

macOS 13 Ventura was released on 2022, introducing the Stage Manager window management feature, Weather, Clock, and Freeform apps, and the release of the Metal 3 API. It introduces Continuity Camera, allowing an iPhone to be used as a camera input for a Mac, and handoff for calls in FaceTime. It introduces a SwiftUI-based rewrite of the System Preferences app, now named System Settings, which received criticism for poor design. It also introduces numerous security features, including alerts for login items and daemons being installed by apps, confirmation prompts when connecting previously unknown USB-C accessories, Lockdown Mode to restrict a handful of risky operating system features, and Rapid Security Response, a feature that aims to support emergency security patches without requiring a full operating system update or even a reboot.