The term soundtrack refers to three related concepts: recorded music accompanying and synchronized to the images of a motion picture, television program or video game; a commercially released soundtrack album of music as featured in the soundtrack of a film or TV show; and the physical area of a film that contains the synchronized recorded sound.

Origin of the term

In movie industry terminology usage, soundtrack is a contraction of "sound track" and is an audio recording created or used in film production or post-production. Initially the dialogue, sound effects, and music in a film each has its own separate track (dialogue track, sound effects track, and music track), and these are mixed together to make what is called the composite track, which is heard in the film. A dubbing track is often later created when films are dubbed into another language. This is also known as a M & E track (music and effects) containing all sound elements minus dialogue which is then supplied by the foreign distributor in the native language of its territory.

The contraction soundtrack came into public consciousness with the advent of so-called "soundtrack albums" in the early 1950s. First conceived by movie companies as a promotional gimmick for new films, these commercially available recordings were labelled and advertised as "music from the original motion picture soundtrack." This phrase was soon shortened to just "original motion picture soundtrack." More accurately such recordings are made from a film's music track, because they usually consist of the isolated music from a film, not the composite (sound) track with dialogue and sound effects.

The abbreviation OST is often used to describe the musical soundtrack on a recorded medium, such as CD, and it stands for Original Soundtrack; however, it is sometimes also used to differentiate the original music heard and recorded versus a rerecording or cover of the music.

Soundtracks are not the same as "cast albums". Original cast recordings are studio made recordings of the songs from a stage musical. The performers sing the score live every night. They do not lip-synch to pre-recorded tracks. Incorrect use of the terminologies creates confusion in the marketplace. For example as of July 2008 there are two albums of the "Mamma Mia" score. The first is the original London cast recording from 1999, while the latest is the film soundtrack. While it is correct to call the soundtrack a cast recording (since it is the cast of the film version) it is incorrect to call the original London cast recording a soundtrack.

Types of Recordings

In the soundtrack genre there are three types of recordings:

1. Musical film soundtracks which concentrate primarily on the songs
   (Examples: “Grease”, “Singin' in the Rain”)
2. Film scores which showcase the background music from non-musicals
   (Examples: “Star Wars”, “”Exodus”)
3. Albums of pop songs heard in whole or part in the background of non-musicals
   (Examples: “Sleepless in Seattle”, “When Harry Met Sally”)