Loops underpin hip hop, electronic music and game soundtracks. A good loop has no audible click or jump where it restarts, and enough variation that repetition does not become tiring.
In games and apps, music often loops while a player stays on a screen. For background use in videos, loops let you extend a track to any length.
Using it in a prompt
Ask for "seamless loop", "no ending" or "ends on the starting chord" when the music has to repeat.