A Pro Tools session is made up of references, or
links, to audio files and other session media. Audio and video files must be stored on suitable Performance volumes and be properly linked in order to be playable in the session.
Files that are stored on volumes not suitable for playback, such as network volumes or CD-ROMs.
Files that cannot be found where the session expects them, either because they have been moved, or because they are stored on volumes that are not currently mounted (offline volumes).
The process of reacquiring missing files is referred to as
relinking. Relinking can involve certain sub-tasks, depending on the situation.