Diegetic music or source music is music in a drama (e.g., film or video game) that is part of the fictional setting and so, presumably, is heard by the characters. The term refers to diegesis, a style of storytelling. The opposite of source music is incidental music or underscoring, which is music heard by the viewer (or player), intended to comment on or highlight the action, but is not to be understood as part of the "reality" of the fictional setting.