There are two main categories of sound in film - diegetic and non-diegetic. Diegetic sound has a source visible on screen like dialogue or ambient noise, while non-diegetic sound like theme music does not. Sound helps create meaning by enhancing emotion, revealing character psychology, and setting atmosphere through location, period, and continuity between scenes. Key sound terminology includes soundtrack, theme music, sound effects, ambient noise, dialogue, voiceover, and techniques like sound bridges, parallel sound, and contrapuntal sound.