A compilation, for the purposes of the MusicBrainz database, covers the following types of releases:
- a collection of recordings from various old sources (not necessarily released) combined together. For example a "best of", retrospective or rarities type release.
- a various artists song collection, usually based on a general theme ("Songs for Lovers"), a particular time period ("Hits of 1998"), or some other kind of grouping ("Songs From the Movies", the "Café del Mar" series, etc).
The MusicBrainz project does not generally consider the following to be compilations:
- a reissue of an album, even if it includes bonus tracks.
- a tribute release containing covers of another artists work.
- a classical release containing new recordings of a classical artists work.
- a release containing two albums and/or EPs (these should be tagged as either an 'album' or an 'EP' depending on the circumstances).
Compilation should be used in addition to, not instead of, other types: for example, a various artists soundtrack using pre-released music should be marked as both a soundtrack and a compilation. As a general rule, always select every secondary type that applies.