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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.
With the rise of digital distribution, distinctions have become more tenuous. The biggest digital music distributor, the iTunes Store, only accepts as singles releases with three tracks or fewer that are less than ten minutes each (with longer releases being classified as EPs or albums). However, releases which do not fit these criteria have been promoted as singles by artists and labels elsewhere, such as on the Bandcamp storefront.
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.

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