Also known as: source music. The opposite of incidental music. It’s music that’s heard both by the viewer and the characters. We are able to listen to the music, as it’s a part of the fictional setting. So, plainly speaking, if you are listening to music and can see someone holding an instrument or singing during the scene you’re watching, then it’s diegetic music. As the main purpose of diegetic music is to narrate a story of its own, think of it like this: It’s music that has leveled up and is presenting us, the viewers, with an inside look of the setting.