Complex sentence: A title track is a song which shares its name with the album on which it appears, or the feature film in which it appears, or the song that runs over the opening credits of a film.
Split into simpler sentences: A title track is a song which shares its name with the album on which it appears. It is also a song which shares its name with the feature film in which it appears, or the song that runs over the opening credits of a film.