A greatest hits album, sometimes called a "best of" album or a catalog album, is a compilation of songs by a particular artist or band. Most often the track list contains previously released recordings with a high degree of notability. However, to increase the appeal, especially to people who already own the original release, it is common to include remixes and/or alternate takes of popular songs; even new material (previously unreleased). At times a greatest hits compilation is the original release for songs that have themselves been released as a single and charted successfully.