Double album
A double album (or double record) is an audio album which spans two units of the primary medium in which it is sold, typically records and compact discs.
A double album is usually, though not always, released as such because the recording is longer than the capacity of the medium. Recording artists often think of double albums as comprising a single piece artistically; however, there are exceptions such as John Lennon's Some Time in New York City and Pink Floyd's Ummagumma (both examples of one studio record and one live album packaged together), and OutKast's Speakerboxxx/The Love Below (effectively two solo albums, one by each member of the duo). A classic example of this idea is Works (Volume One) by Emerson Lake and Palmer, where side one was Keith Emerson, two Greg Lake, three Carl Palmer while side four was by the entire group.