macOS version history
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The history of macOS, Apple's current Mac operating system formerly named Mac OS X until 2011 and then OS X until 2016, began with the company's project to replace its classic Mac OS. That system, up to and including its final release Mac OS 9, was a direct descendant of the operating system Apple had used in its Mac computers since their introduction in 1984. However, the current macOS is a UNIX operating system built on technology that had been developed at NeXT from the 1980s until Apple purchased the company in early 1997.[1]
macOS components derived from BSD include multiuser access, TCP/IP networking, and memory protection.[2]
Although it was originally marketed as simply "version 10" of Mac OS (indicated by the Roman numeral "X"), it has a completely different codebase from Mac OS 9, as well as substantial changes to its user interface. The transition was a technologically and strategically significant one. To ease the transition for users and developers, versions 10.0 through 10.4 were able to run Mac OS 9 and its applications in the Classic Environment, a compatibility layer.
macOS was first released in 1999 as Mac OS X Server 1.0, built using the technologies Apple acquired from NeXT, but did not include the signature Aqua user interface (UI). Mac OS X 10.0 is the first desktop version, aimed at regular users, released in March 2001. Several more distinct desktop and server editions of macOS have been released since. Mac OS X Server is no longer offered as a standalone operating system with the release of Mac OS X 10.7 Lion. Instead, server management tools were provided as an application, available as a separate add-on, until it was discontinued on April 21, 2022, which making it incompatible with macOS 13 Ventura or later.
Releases of macOS, starting with the Intel build of Mac OS X 10.5 Leopard, are certified as Unix systems conforming to the Single UNIX Specification.[3][4][5][6][7]
Mac OS X Lion was the first release to use the shortened OS X name where it was sometimes called OS X Lion, but it was first officially adopted as the sole branding with OS X Mountain Lion. The operating system was further renamed to macOS with the release of macOS Sierra.
Mac OS X 10.0 and 10.1 were given names of big cats as internal code names, Cheetah and Puma. Starting with Mac OS X 10.2 Jaguar, big-cat names were used as marketing names. Beginning with OS X 10.9 Mavericks, names of locations in California were used as marketing names instead.
macOS retained the major version number 10 throughout its development history until the release of macOS 11 Big Sur in 2020, where its major version number was incremented by one with each release. In 2025, Apple unified the versioning across all products, including its other operating systems, to match the year after its WWDC announcement, beginning with macOS 26 Tahoe.
macOS Sequoia was released on September 16, 2024.
- ^ sandaruwani, dilusha (2020-08-06). "Evolution of Mac OS". Medium. Archived from the original on 2023-07-05. Retrieved 2023-07-05.
- ^ "BSD Overview". Archived from the original on 2018-11-07.
- ^ The Open Group. "Mac OS X version 10.5 Leopard on Intel-based Macintosh computers certification". Archived from the original on 2008-05-11. Retrieved 2007-06-12.
- ^ The Open Group. "Mac OS X version 10.6 Leopard on Intel-based Macintosh computers certification". Archived from the original on 2014-11-16. Retrieved 2013-07-11.
- ^ The Open Group. "Mac OS X version 10.8 Mountain Lion on Intel-based Macintosh computers certification". Archived from the original on 2014-11-16.
- ^ The Open Group. "Mac OS X version 10.9 Mavericks on Intel-based Macintosh computers certification". Archived from the original on 2013-11-04. Retrieved 2013-09-18.
- ^ The Open Group. "OS X version 10.10 Yosemite on Intel-based Macintosh computers certification". Archived from the original on 2014-11-10. Retrieved 2014-11-13.