Mac OS : MacOS

Mac OS is Apple Computer's operating system for Apple Macintosh computers. Mac OS was the first commercially successful operating system which used a graphical user interface. The Macintosh team included Bill Atkinson and Jef Raskin.

There are two major versions of the Mac OS: the older and now unsupported Mac OS 9, and the newer Mac OS X (pronunced oh-es-ten). Mac OS X's subsystem is partially based on BSD Unix.

Different people have different memories and emphasis of how the Macintosh was developed, and where the underlying ideas originated. While the connection between the Macintosh and the Alto project at Xerox PARC has been firmly established in the historical record, the earlier contributions of Ivan Sutherland's Sketchpad and Doug Engelbart's On-Line System are no less significant. See History of the GUI.

• QuickDraw
• Finder
• Chooser
• MultiFinder
• Color
• The switch from Motorola 68000 to PowerPC
• Mac OS X and its history
• Mac OS X Server

See also: Mac OS history, OS Advocacy