What is Mac OS?

Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for theirMacintosh line of computer systems.

The original version was integral and an unnamed system software first introduced in 1984 with the original Macintosh, and referred to simply as the "System" software. The Macintosh system software gained an official name in 1996, when Apple branded version 7.6 as Mac OS as part of their Macintosh clone program. The Macintosh, specifically its system software, is credited with popularizing the graphical user interface concept.

Macintosh operating systems have been released in two major series. Up to major revision 9, from 1984 to 2000, it is historically known as Classic Mac OS. Major revision 10, from 2001 to present, is branded OS X (originally referred to as Mac OS X).^[5] Major revisions to the Macintosh OS are now issued as point revisions, that is to say, 10.2 is substantially different from 10.5. Both series share a general interface design and some sharedapplication frameworks for compatibility, but also have deeply different architectures.