Apple's audio and video framework for the Macintosh, introduced in 1991 with the Mac System 7 operating system. QuickTime is the underlying engine in QuickTime Player, the media player that comes with QuickTime, as well as iTunes. There are numerous applications that support QuickTime authoring.

QuickTime originally used Apple's proprietary codecs, but Cinepak, Sorenson and other codecs were added, and QuickTime supports third-party plug-ins. For example, Flip4Mac (www.flip4mac.com) provides QuickTime playback of movies in the Windows Media Video (WMV) format.

Also available for Windows, QuickTime is often downloaded by Windows users as many Web sites feature QuickTime movies to appeal to both a Mac and Windows audience. There is a greater chance that Windows users will already have QuickTime than Mac users will have a media player for Windows formats. QuickTime Player and iTunes do not natively support Windows formats, and Windows Media Player does not natively support QuickTime.

A Very Comprehensive Format
A QuickTime file can contain any kind of continuous motion data such as audio, video, MIDI, animations, virtual reality, Karaoke text and time-based control information. Its time-based synchronization is a major feature of the format, and QuickTime files can even be used to control external events such as lighting. QuickTime files use .QT, .MOV and .MOOV extensions.

MPEG-4 and H.264
Because the QuickTime format was designed for ease of editing, it was chosen as the basis for the MPEG-4 container format. In reciprocation, Apple added MPEG-4 in QuickTime 6 and H.264 (based on MPEG-4) in QuickTime 7. See iTunes, Windows Media, MPEG and H.264.