Incidental music is music in a play, television program, radio program, video game, film or some other form not primarily musical. The term is less frequently applied to film music, with such music being referred to instead as the "film score" or "soundtrack".
Incidental music is often "background" music, and adds atmosphere to the action. It may take the form of something as simple as a low, ominous tone suggesting an impending startling event, or, to enhance the depiction of a story-advancing sequence. It may also include pieces such as overtures, or, music played during scene changes, or at the end of an act, immediately preceding an interlude, as was customary with several nineteenth-century plays. It may also be required in plays that have musicians performing on-stage.