The QuickTime (.mov) file format is a multimedia container format that can store one or more tracks of data such as video, audio, text, and effects. Each track can either contain a digitally encoded media stream, playable using the appropriate codec, or a data reference to a media stream located in another file. In practice this means that it can be easily edited since there is no need to rewrite all media data after editing. Tracks are maintained in a hierarchical data structure consisting of objects called atoms. An atom can be a parent to other atoms or it can contain media or edit data, but it can't contain both.
The ability to contain abstract data references for the media data, and the separation of the media data from the media offsets and the track edit lists means that QuickTime is particularly suited for editing, as it is capable of importing and editing in place (without data copying). Other later-developed media container formats such as Microsoft's Advanced Systems Format or the open source Ogg and Matroska containers lack this abstraction, and require all media data to be rewritten after editing.