Twelve-inch EPs were similar, but generally had between three and five tracks and a length of over 12 minutes. Like seven-inch EPs, these were given titles. EP releases were also issued in cassette and 10-inch vinyl formats. With the advent of the compact disc (CD), more music was often included on "single" releases, with four or five tracks being common, and playing times of up to 25 minutes. These extended-length singles became known as maxi singles and while commensurate in length to an EP were distinguished by being designed to feature a single song, with the remaining songs considered B-sides, whereas an EP was designed not to feature a single song, instead resembling a mini album.