Source music, also known as diegetic music, refers to music that is part of the narrative in a film, television show, or other media. This means that the characters within the story can hear the music, and it often comes from a visible source, such as a radio, a live band, or a character playing an instrument. In contrast to non-diegetic music, which is added for emotional effect and is not heard by the characters, source music helps to create a more immersive experience. It can enhance the storytelling by reflecting the mood or setting, and it often plays a significant role in establishing the atmosphere of a scene.