MOV (Movie) is a container format created by Apple Computer for their QuickTime multimedia platform. Besides accepting natural audio and video, it can contain VRML, synthesized audio (MIDI), menus, chapters, subtitles and other multimedia-related elements.
Up to some years ago, the most popular codecs contained inside a MOV file were Sorenson for video and QDesign or MP3 for audio. Now, these codecs are being slowly replaced by MPEG-4 Visual and AAC, since these codecs became standard in QuickTime 6.0.
MOV has become the standard container for the MPEG-4 multimedia platform - MP4 - with some slight modifications.
The standard and most featureful player for MOV is Apple's QuickTime.