This article is about macOS version 10.0 and later. For Mac OS 9 and earlier, see Classic Mac OS. For the family of Mac operating systems, see Mac operating systems. For the Ugandan school nicknamed "Macos", see Makerere College School.
The first desktop version, Mac OS X 10.0, was released on March 24, 2001. All macOS releases are UNIX 03 certified.[6][7] The derivatives of macOS are Apple's other operating systems: iOS, iPadOS, watchOS, tvOS, and audioOS.
A prominent part of macOS's original brand identity was the use of Roman numeral X, pronounced "ten", as well as code naming each release after species of big cats, and later, places within California.[8] Apple shortened the name to "OS X" in 2011 and then changed it to "macOS" in 2016 to align with the branding of Apple's other operating systems, iOS, watchOS, and tvOS.[9] After sixteen distinct versions of macOS 10, 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 iOS, but is still named after places within California.
^"What Is the I/O Kit?". IOKit Fundamentals. Archived from the original on January 22, 2021. Retrieved September 4, 2018. Apple considered several programming languages for the I/O Kit and chose a restricted subset of C++.
^Mastroianni, Brian (June 13, 2016). "Apple unveils iOS 10, macOS, and more at WWDC 2016". CBS News. Archived from the original on September 25, 2023. Retrieved September 25, 2023. Perhaps one of the announcements that stood out the most was a slight name change. The desktop operating system Mac OS X will now be called macOS to better match with the way the company's other operating systems are named.