OS X (formerly Mac OS X) is the marketing name for Apple's computer OS. Note the proper pronunciation is "ohh ess ten" and not "oh ess ex". it is be replaced by macOS to match its the format of watchOS, tvOS, and ios.

OS X, formerly known as Mac OS X, is an operating system created and distributed by Apple Inc. for their Macintosh computers. Several versions have been released since the 1999 debut of Mac OS X Server 1.0. Although many people pronounce it literally as "Oh ess ex", it is in fact pronounced "Oh ess ten.", as the X in OS X is a Roman numeral for "ten". As of OS X 10.7 Lion, the "Mac" in "Mac OS X" was dropped from all marketing and promotional material, and with OS X 10.8 Mountain Lion, the "Mac" was dropped completely, making the current name "OS X". Upon the release of the 2016 version, the operating system will be known as macOS. The 2016 version will be known as macOS Sierra.

This tag is for any and all questions related to OS X system software. For hardware, use .

Related Tags

There are several -related tags which allow you to specify your operating system version, such as:

It is suggested that if you are asking questions about features of, applications included with, or possible bugs in a particular version of OS X that you add the appropriate tag from the Related list above (such as or ), to allow users to easily distinguish when questions may or may not apply to their own circumstances.

For server-related questions for OS X Server prior to Lion, use .
For questions regarding the Server.app for Lion and newer, use .

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