7-inch records

In music, a single, record single or music single is a type of release, typically a song recording of fewer tracks than an LP record, an album or an EP record. This can be released for sale to the public in a variety of different formats. In most cases, a single is a song that is released separately from an album, although it usually also appears on an album. Typically, these are the songs from albums that are released separately for promotional uses such as digital download or commercial radio airplay and are expected to be the most popular. In other cases a recording released as a single may not appear on an album.

As digital downloading and audio streaming have become more prevalent, it is often possible for every track on an album to also be available separately. Nevertheless, the concept of a single for an album has been retained as an identification of a more heavily promoted or more popular song (or group of songs) within an album collection.

Despite being referred to as a single, singles can include up to as many as three tracks on them. The biggest digital music distributor, iTunes, accepts as many as three tracks less than ten minutes each as a single, as does popular music player Spotify. Any more than three tracks on a musical release or longer than thirty minutes in total running time is either an extended play (EP), or if over six tracks long, it is classed as an album.

The basic specifications of the music single were set in the late 19th century, when the gramophone record began to supersede phonograph cylinders in commercially produced musical recordings. Gramophone discs were manufactured with a range of playback speeds (from 16 rpm to 78 rpm) and in several sizes (including 12-inch/30 cm). By about 1910, however, the 10-inch (25 cm), 78 rpm shellac disc had become the most commonly used format.

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Wikipedia