Theatre music refers to a wide range of music composed or adapted for performance in theatres. Genres of theatre music include opera, ballet and several forms of musical theatre, from pantomime to operetta and modern stage musicals and revues. Another form of theatre music is incidental music, which, as in radio, film and television, is used to accompany the action or to separate the scenes of a play. The physical embodiment of the music is called a score, which includes the music and, if there are lyrics, it also shows the lyrics.