Film music.
Music composed, arranged, compiled or improvised to accompany motion pictures. In the sound cinema, music is recorded as a soundtrack on the film stock and reproduced in exact synchronization with the projected visual image. Film music falls into two broad categories: music contained within the action (known variously as diegetic, source, on-screen, intrinsic or realistic music), and background music amplifying the mood of the scene and/or explicating dramatic developments and aspects of character (termed extra-diegetic or extrinsic music, or underscoring). Both types are capable of generating continuity, narrative momentum and subliminal commentary, and the distinction between them has often been deliberately blurred by composers and directors for dramatic effect.