This article is about the current Apple operating system for Mac computers. For pre-2001 versions, see Classic Mac OS.
Operating system for Apple computers
|OS family||Unix, Macintosh|
|Source model||Closed source (with open source components)|
|Initial release||March 24, 2001; 19 years ago (2001-03-24)|
|Latest release||10.15.6 (Supplemental Update) (19G2021) (August 12, 2020; 34 days ago (2020-08-12)) [±]|
|Latest preview||11.0 beta 6 (20A5364e) (September 3, 2020; 12 days ago (2020-09-03)) [±]|
|Marketing target||Personal computing|
|Available in||39 languages|
[as of macOS Catalina]: Arabic, Catalan, Croatian, Chinese (Hong Kong), Chinese (Simplified), Chinese (Traditional), Czech, Danish, Dutch, English (Australia), English (United Kingdom), English (United States), Finnish, French (Canada), French (France), German, Greek, Hebrew, Hindi, Hungarian, Indonesian, Italian, Japanese, Korean, Malay, Norwegian, Polish, Portuguese (Brazil), Portuguese (Portugal), Romanian, Russian, Slovak, Spanish (Latin America), Spanish (Spain), Swedish, Thai, Turkish, Ukrainian, Vietnamese
|Kernel type||Hybrid (XNU)|
|Default user interface||Aqua (Graphical)|
|License||Commercial software, proprietary software|
|Preceded by||Classic Mac OS, NeXTSTEP|
macOS (/ˌmækoʊˈɛs/; previously Mac OS X and later OS X) is a series of proprietarygraphicaloperating systems developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop, laptop and home computers, and by web usage, it is the second most widely used desktop OS, after Microsoft Windows.
macOS is the second major series of Macintosh operating systems. The first is colloquially called the classic Mac OS, introduced in 1984, the final release of which was Mac OS 9 in 1999. The first desktop version, Mac OS X 10.0, was released in March 2001, with its first update, 10.1, arriving later that year. After this, Apple began naming its releases after big cats, which lasted until OS X 10.8 Mountain Lion. Since OS X 10.9 Mavericks, releases have been named after locations in California. Apple shortened the name to "OS X" in 2012 and then changed it to "macOS" in 2016, adopting the nomenclature that they were using for their other operating systems, iOS, watchOS, and tvOS. The latest version is macOS Catalina, which was publicly released in October 2019.
macOS is based on the Unix operating system and on technologies developed between 1985 and 1997 at NeXT, a company that Apple co-founder Steve Jobs created after leaving Apple in 1985. The "X" in Mac OS X and OS X is the Roman numeral for the number 10 and is pronounced as such. The X was a prominent part of the operating system's brand identity and marketing in its early years, but gradually receded in prominence since the release of Snow Leopard in 2009. In 2020, Apple incremented the major version number to 11 in macOS Big Sur, although it retains the same base as the previous versions of macOS. UNIX 03 certification was achieved for the Intel version of Mac OS X 10.5 Leopard and all releases from Mac OS X 10.6 Snow Leopard up to the current version also have UNIX 03 certification. macOS shares its Unix-based core, named Darwin, and many of its frameworks with Apple's other operating systems.
Releases of Mac OS X from 1999 to 2005 ran on the PowerPC-based Macs of that period. After Apple announced that they were switching to Intel CPUs from 2006 onwards, versions were released for Intel-based Macs with 32-bit and currently 64-bit processors. Versions from macOS 11 (2020) will support both 64-bit Intel and future Macs running 64-bit ARM processors.
Simplified history of Unix-like operating systems
The heritage of what would become macOS had originated at NeXT, a company founded by Steve Jobs following his departure from Apple in 1985. There, the Unix-likeNeXTSTEP operating system was developed, and then launched in 1989. The kernel of NeXTSTEP is based upon the Mach kernel, which was originally developed at Carnegie Mellon University, with additional kernel layers and low-level user space code derived from parts of BSD. Its graphical user interface was built on top of an object-orientedGUI toolkit using the Objective-C programming language.
Throughout the early 1990s, Apple had tried to create a "next-generation" OS to succeed its classic Mac OS through the Taligent, Copland and Gershwin projects, but all were eventually abandoned. This led Apple to purchase NeXT in 1996, allowing NeXTSTEP, then called OPENSTEP, to serve as the basis for Apple's next generation operating system. This purchase also led to Steve Jobs returning to Apple as an interim, and then the permanent CEO, shepherding the transformation of the programmer-friendly OPENSTEP into a system that would be adopted by Apple's primary market of home users and creative professionals. The project was first code named "Rhapsody" and then officially named Mac OS X.
Mac OS X
Launch of Mac OS X
Mac OS X was originally presented as the tenth major version of Apple's operating system for Macintosh computers; current versions of macOS retain the major version number "10". Previous Macintosh operating systems (versions of the classic Mac OS) were named using Arabic numerals, as with Mac OS 8 and Mac OS 9. The letter "X" in Mac OS X's name refers to the number 10, a Roman numeral, and Apple has stated that it should be pronounced "ten" in this context. However, it is also commonly pronounced like the letter "X".
The first version of Mac OS X, Mac OS X Server 1.0, was a transitional product, featuring an interface resembling the classic Mac OS, though it was not compatible with software designed for the older system. Consumer releases of Mac OS X included more backward compatibility. Mac OS applications could be rewritten to run natively via the Carbon API; many could also be run directly through the Classic Environment with a reduction in performance.
The consumer version of Mac OS X was launched in 2001 with Mac OS X 10.0. Reviews were variable, with extensive praise for its sophisticated, glossy Aqua interface, but criticizing it for sluggish performance. With Apple's popularity at a low, the makers of several classic Mac applications such as FrameMaker and PageMaker declined to develop new versions of their software for Mac OS X.Ars Technica columnist John Siracusa, who reviewed every major OS X release up to 10.10, described the early releases in retrospect as 'dog-slow, feature poor' and Aqua as 'unbearably slow and a huge resource hog'.
Apple rapidly developed several new releases of Mac OS X. Siracusa's review of version 10.3, Panther, noted "It's strange to have gone from years of uncertainty and vaporware to a steady annual supply of major new operating system releases." Version 10.4, Tiger, reportedly shocked executives at Microsoft by offering a number of features, such as fast file searching and improved graphics processing, that Microsoft had spent several years struggling to add to Windows with acceptable performance.
As the operating system evolved, it moved away from the classic Mac OS, with applications being added and removed. Considering music to be a key market, Apple developed the iPod music player and music software for the Mac, including iTunes and GarageBand. Targeting the consumer and media markets, Apple emphasized its new "digital lifestyle" applications such as the iLife suite, integrated home entertainment through the Front Row media center and the Safari web browser. With increasing popularity of the internet, Apple offered additional online services, including the .Mac, MobileMe and most recently iCloud products. It later began selling third-party applications through the Mac App Store.
Newer versions of Mac OS X also included modifications to the general interface, moving away from the striped gloss and transparency of the initial versions. Some applications began to use a brushed metal appearance, or non-pinstriped title bar appearance in version 10.4. In Leopard, Apple announced a unification of the interface, with a standardized gray-gradient window style.
In 2006, the first Intel Macs released used a specialized version of Mac OS X 10.4 Tiger.
A key development for the system was the announcement and release of the iPhone from 2007 onwards. While Apple's previous iPod media players used a minimal operating system, the iPhone used an operating system based on Mac OS X, which would later be called "iPhone OS" and then iOS. The simultaneous release of two operating systems based on the same frameworks placed tension on Apple, which cited the iPhone as forcing it to delay Mac OS X 10.5 Leopard. However, after Apple opened the iPhone to third-party developers its commercial success drew attention to Mac OS X, with many iPhone software developers showing interest in Mac development.
In 2007, Mac OS X 10.5 Leopard was the sole release with universal binary components, allowing installation on both Intel Macs and select PowerPC Macs. It is also the final release with PowerPC Mac support. Mac OS X 10.6 Snow Leopard was the first version of OS X to be built exclusively for Intel Macs, and the final release with 32-bit Intel Mac support. The name was intended to signal its status as an iteration of Leopard, focusing on technical and performance improvements rather than user-facing features; indeed it was explicitly branded to developers as being a 'no new features' release. Since its release, several OS X or macOS releases (namely OS X Mountain Lion, OS X El Capitan and macOS High Sierra) follow this pattern, with a name derived from its predecessor, similar to the 'tick-tock model' used by Intel.
In two succeeding versions, Lion and Mountain Lion, Apple moved some applications to a highly skeuomorphic style of design inspired by contemporary versions of iOS while simplifying some elements by making controls such as scroll bars fade out when not in use. This direction was, like brushed metal interfaces, unpopular with some users, although it continued a trend of greater animation and variety in the interface previously seen in design aspects such as the Time Machinebackup utility, which presented past file versions against a swirling nebula, and the glossy translucent dock of Leopard and Snow Leopard. In addition, with Mac OS X 10.7 Lion, Apple ceased to release separate server versions of Mac OS X, selling server tools as a separate downloadable application through the Mac App Store. A review described the trend in the server products as becoming "cheaper and simpler... shifting its focus from large businesses to small ones."
In 2012, with the release of OS X 10.8 Mountain Lion, the name of the system was shortened from Mac OS X to OS X. That year, Apple removed the head of OS X development, Scott Forstall, and design was changed towards a more minimal direction. Apple's new user interface design, using deep color saturation, text-only buttons and a minimal, 'flat' interface, was debuted with iOS 7 in 2013. With OS X engineers reportedly working on iOS 7, the version released in 2013, OS X 10.9 Mavericks, was something of a transitional release, with some of the skeuomorphic design removed, while most of the general interface of Mavericks remained unchanged. The next version, OS X 10.10 Yosemite, adopted a design similar to iOS 7 but with greater complexity suitable for an interface controlled with a mouse.
From 2012 onwards, the system has shifted to an annual release schedule similar to that of iOS. It also steadily cut the cost of updates from Snow Leopard onwards, before removing upgrade fees altogether from 2013 onwards. Some journalists and third-party software developers have suggested that this decision, while allowing more rapid feature release, meant less opportunity to focus on stability, with no version of OS X recommendable for users requiring stability and performance above new features. Apple's 2015 update, OS X 10.11 El Capitan, was announced to focus specifically on stability and performance improvements.
In 2016, with the release of macOS 10.12 Sierra, the name was changed from OS X to macOS to streamline it with the branding of Apple's other primary operating systems: iOS, watchOS, and tvOS. macOS 10.12 Sierra's main features are the introduction of Siri to macOS, Optimized Storage, improvements to included applications, and greater integration with Apple's iPhone and Apple Watch. The Apple File System (APFS) was announced at Apple's annual Worldwide Developers Conference (WWDC) in June 2016 as a replacement for HFS+, a highly criticized file system.
Apple previewed macOS 10.13 High Sierra at WWDC 2017, before releasing it later that year. When running on solid state drives, it uses APFS, rather than HFS+. Its successor, macOS 10.14 Mojave, was released in 2018, adding a dark user interface option and a dynamic wallpaper setting. It was succeeded by macOS 10.15 Catalina in 2019, which replaces iTunes with separate apps for different types of media, and introduces the Catalyst system for porting iOS apps.
In 2020, Apple previewed macOS 11.0 Big Sur at the WWDC 2020. This was the first increment in the primary version number of macOS since the release of Mac OS X Public Beta in 2000. Big Sur brought major changes to the UI and was the first version to run on the ARM instruction set. 
At macOS's core is a POSIX-compliant operating system built on top of the XNUkernel,  with standard Unix facilities available from the command line interface. Apple has released this family of software as a free and open source operating system named Darwin. On top of Darwin, Apple layered a number of components, including the Aqua interface and the Finder, to complete the GUI-based operating system which is macOS.
With its original introduction as Mac OS X, the system brought a number of new capabilities to provide a more stable and reliable platform than its predecessor, the classic Mac OS. For example, pre-emptive multitasking and memory protection improved the system's ability to run multiple applications simultaneously without them interrupting or corrupting each other. Many aspects of macOS's architecture are derived from OPENSTEP, which was designed to be portable, to ease the transition from one platform to another. For example, NeXTSTEP was ported from the original 68k-based NeXT workstations to x86 and other architectures before NeXT was purchased by Apple, and OPENSTEP was later ported to the PowerPC architecture as part of the Rhapsody project.
Prior to macOS High Sierra, and on drives other than solid state drives (SSDs), the default file system is HFS+, which it inherited from the classic Mac OS. Operating system designer Linus Torvalds has criticized HFS+, saying it is "probably the worst file system ever", whose design is "actively corrupting user data". He criticized the case insensitivity of file names, a design made worse when Apple extended the file system to support Unicode.
The Darwin subsystem in macOS manages the file system, which includes the Unix permissions layer. In 2003 and 2005, two Macworld editors expressed criticism of the permission scheme; Ted Landau called misconfigured permissions "the most common frustration" in macOS, while Rob Griffiths suggested that some users may even have to reset permissions every day, a process which can take up to 15 minutes. More recently, another Macworld editor, Dan Frakes, called the procedure of repairing permissions vastly overused. He argues that macOS typically handles permissions properly without user interference, and resetting permissions should only be tried when problems emerge.
The architecture of macOS incorporates a layered design: the layered frameworks aid rapid development of applications by providing existing code for common tasks. Apple provides its own software development tools, most prominently an integrated development environment called Xcode. Xcode provides interfaces to compilers that support several programming languages including C, C++, Objective-C, and Swift. For the Mac transition to Intel processors, it was modified so that developers could build their applications as a universal binary, which provides compatibility with both the Intel-based and PowerPC-based Macintosh lines. First and third-party applications can be controlled programmatically using the AppleScript framework, retained from the classic Mac OS, or using the newer Automator application that offers pre-written tasks that do not require programming knowledge.
- ^Messages 8.0bArchived April 17, 2017, at the Wayback Machine was a beta release that only functioned from February 16 to December 12, 2012. Afterwards, users could either revert to iChat or upgrade to a newer version of OS X (10.8 "Mountain Lion" for US$19.99, or 10.9 "Mavericks" or newer for free) to continue using Messages.
- ^Keynote 1.0 is the only iLife program that is compatible with Mac OS X 10.2 "Jaguar". Two minor updates, 1.1 and 1.1.1, can be applied to this version.
- ^iTunes 2.0.4 can only run if Classic is installed. Otherwise, Mac OS X 10.0 can only run iTunes 1.1.1 natively.
Apple offered two main APIs to develop software natively for macOS: Cocoa and Carbon. Cocoa was a descendant of APIs inherited from OPENSTEP with no ancestry from the classic Mac OS, while Carbon was an adaptation of classic Mac OS APIs, allowing Mac software to be minimally rewritten to run natively on Mac OS X.
The Cocoa API was created as the result of a 1993 collaboration between NeXT Computer and Sun Microsystems. This heritage is highly visible for Cocoa developers, since the "NS" prefix is ubiquitous in the framework, standing variously for NeXTSTEP or NeXT/Sun. The official OPENSTEP API, published in September 1994, was the first to split the API between Foundation and ApplicationKit and the first to use the "NS" prefix. Traditionally, Cocoa programs have been mostly written in Objective-C, with Java as an alternative. However, on July 11, 2005, Apple announced that "features added to Cocoa in Mac OS X versions later than 10.4 will not be added to the Cocoa-Java programming interface." macOS also used to support the Java Platform as a "preferred software package"—in practice this means that applications written in Java fit as neatly into the operating system as possible while still being cross-platform compatible, and that graphical user interfaces written in Swing look almost exactly like native Cocoa interfaces. Since 2014, Apple has promoted its new programming language Swift as the preferred language for software development on Apple platforms.
Apple's original plan with macOS was to require all developers to rewrite their software into the Cocoa APIs. This caused much outcry among existing Mac developers, who threatened to abandon the platform rather than invest in a costly rewrite, and the idea was shelved. To permit a smooth transition from Mac OS 9 to Mac OS X, the CarbonApplication Programming Interface (API) was created. Applications written with Carbon were initially able to run natively on both classic Mac OS and Mac OS X, although this ability was later dropped as Mac OS X developed. Carbon was not included in the first product sold as Mac OS X: the little-used original release of Mac OS X Server 1.0, which also did not include the Aqua interface. Apple limited further development of Carbon from the release of Leopard onwards and announced that Carbon applications would not run at 64-bit. A number of macOS applications continued to use Carbon for some time afterwards, especially ones with heritage dating back to the classic Mac OS and for which updates would be difficult, uneconomic or not necessary. This included Microsoft Office up to Office 2016, and Photoshop up to CS5. Early versions of macOS could also run some classic Mac OS applications through the Classic Environment with performance limitations; this feature was removed from 10.5 onwards and all Macs using Intel processors.
Because macOS is POSIX compliant, many software packages written for the other Unix-like systems including Linux can be recompiled to run on it, including much scientific and technical software. Third-party projects such as Homebrew, Fink, MacPorts and pkgsrc provide pre-compiled or pre-formatted packages. Apple and others have provided versions of the X Window System graphical interface which can allow these applications to run with an approximation of the macOS look-and-feel. The current Apple-endorsed method is the open-source XQuartz project; earlier versions could use the X11 application provided by Apple, or before that the XDarwin project.
Applications can be distributed to Macs and installed by the user from any source and by any method such as downloading (with or without code signing, available via an Apple developer account) or through the Mac App Store, a marketplace of software maintained by Apple through a process requiring the company's approval. Apps installed through the Mac App Store run within a sandbox, restricting their ability to exchange information with other applications or modify the core operating system and its features. This has been cited as an advantage, by allowing users to install apps with confidence that they should not be able to damage their system, but also as a disadvantage due to blocking the Mac App Store's use for professional applications that require elevated privileges. Applications without any code signature cannot be run by default except from a computer's administrator account.
Apple produces macOS applications. Some are included with macOS and some sold separately. This includes iWork, Final Cut Pro, Logic Pro, iLife, and the database application FileMaker. Numerous other developers also offer software for macOS.
In 2018 Apple introduced an application layer, reportedly codenamed Marzipan, to port iOS apps to macOS. macOS Mojave included ports of four first-party iOS apps including Home and News, and it was announced that the API would be available for third-party developers to use from 2019.
|Operating system ||Supported systems||RAM requirement |
- 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 or newer)
|4 GB |
- MacBook (Early 2015 or newer)
- MacBook Air (Mid 2012 or newer)
- MacBook Pro (Mid 2012 or newer)
- Mac mini (Late 2012 or newer)
- iMac (Late 2012 or newer)
- iMac Pro (2017)
- Mac Pro (Late 2013 or newer)
- MacBook (Early 2015 or newer)
- MacBook Air (Mid 2012 or newer)
- MacBook Pro (Mid 2012 or newer)
- Mac mini (Late 2012 or newer)
- iMac (Late 2012 or newer)
- iMac Pro (2017)
- Mac Pro (Late 2013; Mid 2010 and Mid 2012 models
with recommended Metal-capable graphics cards)
|2 GB |
|10.12 – 10.13|
- MacBook (Late 2009 or newer)
- MacBook Pro (Mid 2010 or newer)
- MacBook Air (Late 2010 or newer)
- Mac mini (Mid 2010 or newer)
- iMac (Late 2009 or newer)
- Mac Pro (Mid 2010 or newer)
|10.8 – 10.11|
- MacBook (Early 2015) (Only 10.10 and 10.11)
- MacBook (Late 2008 Aluminum, or Early 2009 or newer)
- MacBook Pro (Mid/Late 2007 or newer)
- MacBook Air (Late 2008 or newer)
- Mac mini (Early 2009 or newer)
- iMac (Mid 2007 or newer)
- Mac Pro (Early 2008 or newer)
- Xserve (Early 2009)
|10.7||Intel Macs (64-bit)|
Rosetta support dropped from 10.7 and newer.
|10.6||Intel Macs (32-bit or 64-bit)||1 GB |
|10.5||G4, G5 and Intel Macs (32-bit or 64-bit) at 867 MHz or faster|
Classic support dropped from 10.5 and newer.
|512 MB |
|10.4||Macs with built-in FireWire and either a New World ROM or Intel processor ||256 MB |
|10.3||Macs with a New World ROM||128 MB |
|10.0 – 10.2||G3, G4 and G5 iBook and PowerBook, Power Mac and iMac|
(except PowerBook G3 "Kanga")
Tools such as XPostFacto and patches applied to the installation media have been developed by third parties to enable installation of newer versions of macOS on systems not officially supported by Apple. This includes a number of pre-G3 Power Macintosh systems that can be made to run up to and including Mac OS X 10.2 Jaguar, all G3-based Macs which can run up to and including Tiger, and sub-867 MHz G4 Macs can run Leopard by removing the restriction from the installation DVD or entering a command in the Mac's Open Firmware interface to tell the Leopard Installer that it has a clock rate of 867 MHz or greater. Except for features requiring specific hardware such as graphics acceleration or DVD writing, the operating system offers the same functionality on all supported hardware.
As most Mac hardware components, or components similar to those, since the Intel transition are available for purchase, some technology-capable groups have developed software to install macOS on non-Apple computers. These are referred to as Hackintoshes, a portmanteau of the words "hack" and "Macintosh". This violates Apple's EULA (and is therefore unsupported by Apple technical support, warranties etc.), but communities that cater to personal users, who do not install for resale and profit, have generally been ignored by Apple. These self-made computers allow more flexibility and customization of hardware, but at a cost of leaving the user more responsible for their own machine, such as on matter of data integrity or security.Psystar, a business that attempted to profit from selling macOS on non-Apple certified hardware, was sued by Apple in 2008.
Steve Jobs talks about the transition to Intel processors.
In April 2002, eWeek announced a rumor that Apple had a version of Mac OS X code-named Marklar, which ran on Intel x86 processors. The idea behind Marklar was to keep Mac OS X running on an alternative platform should Apple become dissatisfied with the progress of the PowerPC platform. These rumors subsided until late in May 2005, when various media outlets, such as The Wall Street Journal and CNET, announced that Apple would unveil Marklar in the coming months.
On June 6, 2005, Steve Jobs announced in his keynote address at WWDC that Apple would be making the transition from PowerPC to Intel processors over the following two years, and that Mac OS X would support both platforms during the transition. Jobs also confirmed rumors that Apple had versions of Mac OS X running on Intel processors for most of its developmental life. Intel-based Macs would run a new recompiled version of OS X along with Rosetta, a binary translation layer which enables software compiled for PowerPC Mac OS X to run on Intel Mac OS X machines. The system was included with Mac OS X versions up to version 10.6.8. Apple dropped support for Classic mode on the new Intel Macs. Third party emulation software such as Mini vMac, Basilisk II and SheepShaver provided support for some early versions of Mac OS. A new version of Xcode and the underlying command-line compilers supported building universal binaries that would run on either architecture.
PowerPC-only software is supported with Apple's official emulation software, Rosetta, though applications eventually had to be rewritten to run properly on the newer versions released for Intel processors. Apple initially encouraged developers to produce universal binaries with support for both PowerPC and Intel. PowerPC binaries suffer a performance penalty when run on Intel Macs through Rosetta. Moreover, some PowerPC software, such as kernel extensions and System Preferences plugins, are not supported on Intel Macs at all. Some PowerPC applications would not run on macOS at all. Plugins for Safari need to be compiled for the same platform as Safari, so when Safari is running on Intel, it requires plug-ins that have been compiled as Intel-only or universal binaries, so PowerPC-only plug-ins will not work. While Intel Macs can run PowerPC, Intel, and universal binaries, PowerPC Macs support only universal and PowerPC builds.
Support for the PowerPC platform was dropped following the transition. In 2009, Apple announced at WWDC that Mac OS X 10.6 Snow Leopard would drop support for PowerPC processors and be Intel-only. Rosetta continued to be offered as an optional download or installation choice in Snow Leopard before it was discontinued with Mac OS X 10.7 Lion. In addition, new versions of Mac OS X first- and third-party software increasingly required Intel processors, including new versions of iLife, iWork, Aperture and Logic Pro.
Rumors of Apple shifting Macs to the ARM processors used by iOS devices began circulating as early as 2011, and ebbed and flowed throughout the 2010s. Rumors intensified in 2020, when numerous reports announced that the company would announce its shift to its custom processors at WWDC.
Apple officially announced its shift to processors designed in-house on June 22, 2020 at WWDC 2020, with the transition planned to last for two years. The first release of macOS to support ARM will be macOS Big Sur.
Aqua user interface