In music, a single is a type of release, typically a song recording of fewer tracks than an LP record or an album. One can be released for sale to the public in a variety of formats. In most cases, a single is a song that is released separately from an album, although it usually also appears on an album. In other cases a recording released as a single may not appear on an album.
Despite being referred to as a single in the era of music downloads, singles can include up to as many as three tracks. The biggest digital music distributor, the iTunes Store, accepts as many as three tracks that are less than ten minutes each as a single. Any more than three tracks on a musical release or thirty minutes in total running time is an extended play (EP) or, if over six tracks long, an album.
Historically, when mainstream music was purchased via vinyl records, singles would be released double-sided, i.e. there was an A-side and a B-side, on which two songs would appear, one on each side.