Common abbreviation of サウンドトラック, used in everyday conversation about movies, games, and anime music.
See also: サウンドトラック
The soundtrack for this movie is really good, isn't it?
サントラを聴きながら勉強するのが好きです。
I like studying while listening to soundtracks.
I often listen to this anime's soundtrack.
After watching the movie, I bought the soundtrack.
That song is included on the game's soundtrack.