In classical music, there’s a good chance that you’ll hear the opening music return at the end. It might be: A) literally repeated note for note or B) altered in some way (but let’s keep this second type under the “repetition” umbrella, too, for simplicity’s sake).
TIME OUT for a delicious food analogy:
Opening and closing music = outer donut Middle music = custard filling
Okay, so why do composers repeat the opening music?
Well for one thing, I think music sounds differently each time it comes back, even if it’s repeated note for note. It’s like when
you go on vacation. You start out at home, go someplace else for a while, and then return home. I don’t know about you, but home always feels different by the time I get back (sometimes in a good way and sometimes in a not so good way if I really enjoyed the vacation).