[[Category:Operating Systems]] '''macOS''' is the [[:Category:Operating Systems|operating system]] used in [[wp:Macintosh|Macintosh]] computers since their introduction in 1984. Some appliances (notably the [[wp:iPhone|iPhone]] and [[wp:iPad|iPad]]) also run derivative versions of Mac OS, named iOS. The current version is '''[[wp:macOS High Sierra|macOS High Sierra]]''' (10.13), which is derived from [[wp:NeXTSTEP|NeXTSTEP]], and has a [[wp:Mach (kernel)|Mach]]-based microkernel running a [[BSD]] compatibility layer. Most applications are written in [[:Category:Objective-C|Objective-C]] and [[:Category:Swift|Swift]] using the [[Cocoa]] framework.

Versions of macOS from 10.0 to 10.11 were branded as '''Mac OS X''', and the current release is still unofficially referred to as such. Previous versions were simply called '''Mac OS''', while the oldest versions were referred to as '''System''' followed by the version number, e.g. "[[wp:System 7|System 7]]".

"'''Mac'''" is a term which describes the broader class of Apple computer hardware and their Macintosh operating systems.

=Older versions=

Pre-X versions of Mac OS ([[wp:Mac OS 9|Mac OS 9]] and lower) were written in-house at Apple and were based in part on the slightly earlier [[wp:Apple Lisa|Lisa Office System]]. "Classic" Mac OS is still in use on many older Macs, especially 68k Macs (Macs with a [[wp:Motorola 68000 family|Motorola 680x0]] processor), which are unable to run versions newer than 8.1. (In fact, many older Macs can't run [[wp:Mac OS 8|OS 8]] at all.) Depending on the specific model, [[wp:PowerPC|PowerPC]] Macs support anywhere from [[wp:System 7|System 7.1.2]] up to OS X 10.5. (OS X 10.6 dropped support for PowerPC Macs, although an emulation layer called [[wp:Rosetta (software)|Rosetta]] was included through 10.6.8 to run PowerPC apps on Intel Macs.)

=See also=

• [[wp:Macintosh operating systems|Wikipedia's Mac OS page]]