MacOS

macOS, named Mac OS X from 2001 to 2012 and OS X until 2016, is an operating system (OS) for computers made by Apple Inc. These are called Macintosh computers, or Macs. It differs from other computers, as macOS is supposed to run only on Macs and not on other computers. However, people have made macOS run on computers that are not Macs. This is called Hackintosh and violates macOS' license agreement.

macOS first came out in 2001, and is completely different from the "classic" Mac OS that it replaced. Unlike the first operating system, macOS (since OS X) is based on the UNIX operating system (current versions have UNIX 03 certification) and on technologies developed between 1985 and 1997 at NeXT, a company that Apple co-founder Steve Jobs made 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 core of macOS is an open source OS called Darwin, but Darwin itself cannot run macOS software.

macOS releases are named after types of big cats, or California landmarks, and has a version number that starts with 10.0, 11.x, 12.0, 13.0, 14.0 & 15.0. The latest version of macOS is macOS Sequoia (15.0).

 Development 
Throughout the early 1990s, Apple had tried to make a "next-generation" OS to replace its classic Mac OS. 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. That company was also founded by Steve Jobs following his departure from Apple in 1985. There, the Unix-like NeXTSTEP operating system was developed, and then launched in 1989 (the "classic" Mac OS is much older, as it came out in 1984). 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 from parts of Berkeley Software Distribution (BSD). Its graphical user interface was built on top of an object-oriented GUI toolkit using the  programming language.

 Versions 
+macOS version informationVersionCodenameDate announcedRelease dateMost recent versionRhapsody Developer ReleaseGrail1Z4 / Titan1UApril 30, 1996August 31, 1997DR2 (May 14, 1998)Mac OS X Server 1.0HeraMarch 16, 19981.2v3 (October 27, 2000)Mac OS X Developer PreviewKodiakMarch 16, 1999DP4 (April 5, 2000)Public BetaKodiak/CheetahJanuary 5, 2000September 13, 2000Mac OS X 10.0CheetahMarch 24, 200110.0.4 (June 22, 2001)Mac OS X 10.1PumaJuly 18, 2001September 25, 200110.1.5 (June 6, 2002)Mac OS X 10.2JaguarMay 6, 2002August 24, 200210.2.8 (October 3, 2003)Mac OS X 10.3PantherJune 23, 2003October 24, 200310.3.9 (April 15, 2005)Mac OS X 10.4TigerMay 4, 2004April 29, 200510.4.11 (November 14, 2007)Mac OS X 10.5LeopardJune 26, 2006October 26, 200710.5.8 (August 5, 2009)Mac OS X 10.6Snow LeopardJune 9, 2008August 28, 200910.6.8 v1.1 (July 25, 2011)Mac OS X 10.7LionOctober 20, 2010July 20, 201110.7.5 (September 19, 2012)OS X 10.8Mountain LionFebruary 16, 2012July 25, 201210.8.5 (12F45) (October 3, 2013)OS X 10.9MavericksJune 10, 2013October 22, 201310.9.5 (13F1112) (September 18, 2014)OS X 10.10YosemiteJune 2, 2014October 16, 201410.10.5 (14F27) (August 13, 2015)OS X 10.11El CapitanJune 8, 2015September 30, 201510.11.6 (15G1510) (May 15, 2017)macOS 10.12SierraJune 13, 2016September 20, 201610.12.6 (16G1212) (July 19, 2017)macOS 10.13High SierraJune 5, 2017September 25, 201710.13.6 (17G65) (July 9, 2018)macOS 10.14MojaveJune 4, 2018September 24, 201810.14.6 (18G87) (August 1, 2019)macOS 10.15CatalinaJune 3, 2019October 7, 201910.15.5 Supplemental Update (19F101) (June 1, 2020)macOS 11.0Big SurJune 22, 2020November 12, 202011.7.9 (20G1426) (July 24, 2023)macOS 12.0MontereyJun 7, 2021October 25, 202112.6.8 (21G725) (July 24, 2023)macOS 13.0VenturaJun 6, 2022October 24, 202213.7.1 (22H210) (September 17, 2024)macOS 14.0SonomaJune 5, 2023September 26, 202314.7.1 (23H209) (September 23, 2024)macOS 15.0SequoiaJune 10, 2024September 16, 202415.1 beta 1 (24B5046F) (September 17, 2024)macOS 26.0TahoeJune 9, 2025September 15, 202526.2 Release Candidate (25C56) (December 3, 2025)

 Public Beta: "Kodiak" 
On September 13, 2000, Apple released a $29.95 preview of Mac OS X to ask users what they think of the new operating system so far. Apple stopped the Public Beta in March 2001 because of the recent release of OS X 10.0.

 Version 10.0: "Cheetah" 
On March 24, 2001 Apple released Mac OS X for the first time aka OS X v10.0 (codename Cheetah), but unfortunately, it was a failure due to its many computer bugs and glitches and its slow performance. Luckily this operating system version only stayed on the market up until September when it was moved up to a "higher level".

 Version 10.1: "Puma" 
Due to many problems and complaints about Cheetah, Apple directly got to work on releasing Puma, the next big cat in Mac OS X. It was released on September 24, 2001. Apple gave 10.0 users a free Mac OS X v10.1 install CD to make up for the flawed operating system before. As of January 7, 2002, Apple said Mac OS 9 and other previous operating systems from Apple were "going in the computer scrapyard" by the end of the month (January 31, 2002) and OS X would be the default and only operating system available on all Macs.

 Version 10.2: "Jaguar" 
Mac OS X 10.2 Jaguar was released on August 24, 2002 and was the first to have its codename in the version branding. The Happy Mac (which formerly appeared when a Mac was starting up) was replaced with a large gray apple logo with the startup sequence of OS X 10.2 Jaguar.

 Version 10.3: "Panther" 
Mac OS X 10.3 Panther was released on October 24, 2003 and was one of the biggest updates to OS X yet. It featured a new brushed metal interface, an updated Finder, and many more features from Jaguar the year before.

 Version 10.4: "Tiger" 
Tiger was released on April 29, 2005 and as stated by Apple, featured more than 200 new features. Among the new features, Tiger introduced Spotlight, Dashboard, Smart Folders, updated Mail program with Smart Mailboxes, QuickTime 7, Safari 2, Automaton, Voice-over, Core Image and Core Video. Apple released the first Power Intel Macs for Tiger on January 10, 2006. Tiger ran swell on these computers. It was also the last operating system to support the Aqua color scheme.

 Version 10.5: "Leopard" 
Mac OS X v10.5 Leopard was released on October 26, 2007. It was completely redesigned featuring a 3D Dock, a new purple color scheme, and over 200 new features. It had both support for PowerPC and Intel Macs too. Leopard was the last release to have support for PowerPC.

 Version 10.6: "Snow Leopard" 
Mac OS X Snow Leopard was released on August 28, 2009, and rather than featuring changes to the appearance, it featured "Under the hood" changes. Snow Leopard dropped support for PowerPC Macs too.

 Version 10.7: "Lion" 
OS X Lion was first shown to the public at the "Back to The Mac" event in 2010, announced more at WWDC 2011, and released on July 20, 2011. It featured iOS-like features such as the Launchpad, the Magic Trackpad coming to MacBooks, and a new solar system color scheme. Apple also removed Rosetta making it impossible to use PowerPC.

 Version 10.8: "Mountain Lion" 
OS X Mountain Lion was announced on February 18, 2012, and released on July 25, 2012. It adds more features from iOS 5 and 6 to the Mac such as notifications, messaging, game center, and gaming with people on iPhones, iPods, and iPads.

 Version 10.9: "Mavericks" 
OS X Mavericks was announced on June 10, 2013 at the 2013 Worldwide Developers Conference. It adds the Maps and iBooks applications, as well as new Finder features, better multi-display support, power improvements, and a new version of Safari. It was released on October 22, 2013. It was the first macOS version that was free.

 Version 10.10: "Yosemite" 
OS X Yosemite was announced in June 2014 at the 2014 Worldwide Developers Conference. It was in beta form for developers and those enrolled in the public beta programme to test until October 16, 2014 when it was released. It introduces a new flat design, following the aesthetic introduced with iOS 7.

 Version 10.11: "El Capitan" 
OS X 10.11 El Capitan was released on September 30, 2015 after being announced on June 8, 2015. Similar to Mac OS X 10.6 Snow Leopard, Apple described this release as containing "refinements to the Mac experience" and "improvements to system performance" rather than new features. Refinements include public transport built into the Maps application, GUI improvements to the Notes application, adopting San Francisco as the system font for clearer legibility, and the introduction of System Integrity Protection. The Metal API, first introduced in iOS 8, was also included in this operating system for "all Macs since 2012".

 Version 10.12: "Sierra" 
macOS 10.12 Sierra was announced on June 12, 2016 and released to the public on September 20, 2016. New features include the addition of Siri, Optimized Storage, and updates to Photos, Messages, and iTunes

 Version 10.13: "High Sierra" 
The fall release of macOS 10.13 High Sierra was announced on June 5, 2017 at Apple's WWDC event. On September 12, 2017 at Apple's iPhone event, they announced its release to be September 25, 2017. Like OS X El Capitan and OS X Mountain Lion, High Sierra is a refinement-based update having very few new features. High Sierra uses the new Apple File System and includes enhancements to Safari, Photos, and Mail, among other changes.

 Version 10.14: "Mojave" 
Released on September 24, 2018. There are many additional features to the existing macOS apps. Some highlights are Dark Mode (UI theme & appearance), time shifts reflecting the hour of the day (desktop background), file stacks, edit features in quick look, continuity camera and Group FaceTime features also adds the screenshot app.

 Version 10.15: "Catalina" 
Released on October 7, 2019. This OS is included with lots of additional new features like sharing your screen to iPad (Sidecar) and is capable of running iPad apps. Catalina is the first version of macOS to exclusively support 64-bit applications. MacOS Catalina also split up iTunes into 3 apps: Music, Podcasts and Movies. Because of the removal of iTunes, syncing your devices is done in Finder.

 Version 11.0: "Big Sur" 
Released on November 12, 2020, macOS Big Sur changes the version number from 10 to 11. It now supports the ARM64 instruction set architecture (ISA), as Apple is transitioning the Mac to its own Apple Silicon based on the ARM64 platform. It brings the biggest design changes since the introduction of macOS (then called Mac OS X).

 Version 12.0: "Monterey" 
Released on October 25, 2021. macOS Monterey changes the version number from 11 to 12.

 Version 13.0: "Ventura" 
Released on October 24, 2022, macOS Ventura changes the version number from 12 to 13.

 Version 14.0: "Sonoma" 
Released on September 26, 2023, macOS Sonoma brings a set of new features to the Mac. With macOS Sonoma, desktop widgets is released which unlock a new way to personalize the Mac and get more done. Stunning new screen savers, updates to video conferencing and Safari, optimized gaming, among several other useful features are also released. 
 Version 15.0: "Sequoia" 
Released on September 16, 2024, macOS Sequoia changes the version number from 14 to 15.

 Version 26.0:  "Tahoe" 
Released on September 15, 2025, macOS Tahoe changes the version number from 15 to 26. Tahoe also brings a new Liquid Glass design to the macOS.

 Architecture 
The core of macOS is a POSIX-compliant operating system. Apple named it Darwin. Apple built it on top of the XNU kernel. The standard Unix facilities can be used from the command line interface. Apple has released Darwin as a free and open source operating system. Apple put many components on top of Darwin, including the Aqua interface and the Finder. These complete the GUI-based operating system which is macOS.

Darwin manages the file system in macOS. A part of the file system is the Unix permissions layer. It controls what users and parts of the operating system can do with the files. In 2003 and 2005, two Macworld editors criticized its permission system. Ted Landau called permissions that are set up wrong "the most common frustration" in macOS. Rob Griffiths suggested that some users may have to reset permissions every day. He said this can take up to 15 minutes. Later, Dan Frakes wrote in Macworld that people try repairing permissions too often. He argues that they should try resetting permissions only when there are problems. He says macOS usually sets correct permissions.

The architecture of macOS has many layers. The layers provide code for common tasks. They make the development of applications faster. Apple made software development tools for macOS. Xcode, an integrated development environment, stand out. Developers use Xcode to use compilers. It supports many programming languages, including C, C++, Objective-C, and Swift. Apple made changes to Xcode for the Apple–Intel transition. Developers could build their applications as a universal binary. It lets the applications work on both Intel-based and PowerPC-based Macintosh. Users have two ways to programmatically control applications. The AppleScript framework was a part of the classic Mac OS. The newer Automator application offers pre-written tasks. Users do not need to know programming to use these tasks.

 References 

 Related pages 
 Macintosh

 Other websites 
 Apple Inc.
 macOS


Category:Unix
Category:BSD