Playlist Overview :
A track has a series of Regions on a timeline. Each Region represents a part of a sound file (or MIDI file). The order of these regions, and additional region properties such as gain/controller curves, fades, and mute/unmute status, are stored in the track’s playlist.
Tracks can have multiple playlists, and you can create a new playlist, copy a playlist from another track, or link 2 tracks to use the same playlist. This provides some interesting possibilities. Some users like to use playlists to separate the different “takes” of a tracking session. Some users like to link playlists so that the tracks can be processed separately, but any edit on one track will be applied to the other.
Clicking the “P” button on a track header opens the Playlist menu: