In recorded music, one finds three main categorisations of a release according to both its length (duration) and the number of tracks: Album, Extended Play (EP) and Single.
Unfortunately, and in spite of the tendency to standardization, there is no 100% consensus. The concepts of album, EP and single are in change, following (roughly) the evolution of the support of recorded music (from physical media to digital only). This means that the definitions of these three concepts changed over time (and obviously there is no guarantee that they will not change in the future).
Besides, there is no absolute unanimity. According to different sources, the same release will be called single or Extended Play in different platforms. Here I will concentrate on the digital platforms iTunes and (in part) Spotify, arguably two of the most important stores in the music industry today (2018).
A Single is any release that contains 1 to 3 tracks that are less than 10 minutes each. As a consequence, the entire release will be less than 30 minutes. However, if your release is less than 30 minutes BUT one of its tracks is longer than 10 minutes, it will not be classified as single (but as EP).
For instance, a 3-track release with these durations: 7-11-5 is NOT a single (because one track is over 10 minutes).
There is a little contradiction in this definition of single. Historically, a typical single in physical format would have 2 sides: A and B. The idea of a 3 sides single would be considered miraculous in the vinyl era.
An Extended Play (EP) is any release that has either:
- 1 to 3 tracks, with one track at least 10 minutes long, BUT has a total playing time of up to 30 minutes.
- 4 to 6 tracks with a total running time of up to 30 minutes.
Interestingly, however, Spotify would classify a release as a Single if it has 5 or fewer tracks. So the same release can (and will) be classified differently in different platforms. Again, this might (and possibly will) change with time.
An Album is any release that has either
- 7 or more tracks (independently of the duration)
- 1 to 6 tracks BUT a duration of over 30 minutes.
There definitions have funny consequences. For instance, a track over 30 minutes long is not a single, is an album. Unrealistic? Yes in pop music or in rock, but less unrealistic in classical music: for instance, the piano sonata in B minor by Franz Liszt (a piece in a single movement) has a duration of 30 to 32 minutes, depending on who performs it. Sometimes, this single-movement piece is recorded in several tracks.
You find another weird scenarios: a release could be an album if it has (say) 12 songs, even if its duration is of (say) 9 minutes. Is the case with my own piano album Aphorismen: 12 tracks and a length of 8:47.
Obviously, I used several sources to write this little article. I didn't copy the contents, however! This would be impossible, since different sources state different things.