Compilation album is a general term used to refer to a music release made of up songs not intended to be seen as a single work. Compilation albums - frequently referred to as "comps" - are often made up of tracks by various artists, though they can sometimes feature a single artist. The former case includes things like soundtracks, label samplers and theme albums. In the latter case, a comp can be a retrospective, greatest hits or sampler of an artists' career, a collection of unreleased tracks, or some combination of these.
Compilation albums can be difficult to put together, as the label releasing the comp must secure permission from all of the parties involved. This can mean juggling demands of a long list of publishers, labels and musicians, who sometimes have divergent interests. This fact is true even of a single artist compilation album if the artist has worked with more than one label over the course of their careers.
