7" EP

An extended play (EP) is a musical recording that contains more tracks than a single, but is usually unqualified as an album or LP. EPs generally do not contain as many tracks as albums, and are considered "less expensive and time-consuming" for an artist to produce than an album. An EP originally referred to specific types of vinyl records other than 78 rpm standard play (SP) and LP, but it is now applied to mid-length CDs and downloads as well.

Ricardo Baca of The Denver Post said, "EPs—originally extended-play 'single' releases that are shorter than traditional albums—have long been popular with punk and indie bands." In the United Kingdom, the Official Chart Company defines a boundary between EP and album classification at 25 minutes of length or four tracks (not counting alternative versions of featured songs, if present).

EPs were released in various sizes in different eras. The earliest multi-track records, issued around 1919 by Grey Gull Records, were vertically cut 78 rpm discs known as "2-in-1" records. These had finer than usual grooves, like Edison Disc Records. By 1949, when the 45 rpm single and 33 ¹⁄₃ rpm LP were competing formats, seven-inch 45 rpm singles had a maximum playing time of only about four minutes per side.

Partly as an attempt to compete with the LP introduced in 1948 by rival Columbia, RCA Victor introduced "Extended Play" 45s during 1952. Their narrower grooves, achieved by lowering the cutting levels and sound compression optionally, enabled them to hold up to 7.5 minutes per side—but still be played by a standard 45 rpm phonograph. These were usually 10-inch LPs (released until the mid-1950s) split onto two seven-inch EPs or 12-inch LPs split onto three seven-inch EPs, either sold separately or together in gatefold covers. This practice became much less common with the advent of triple-speed-available phonographs.

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Wikipedia