Pretty much all chess players learn early on that rooks are more valuable than minor pieces (knights and bishops). Winning a rook for a minor piece is called winning "the exchange". We learn how to use our knights to fork and we grow to believe that winning a game up an exchange is the proper order of things in the chess universe.
At some point we learn that strong players will sometimes sacrifice a rook for a minor piece - sacrificng the exchange. Sometimes there are immediate consequences and the exchange sac is not so difficult to understand, but often the sac is for a long term positional advantage that is much more mysterious.
While I don't fully comprehend the exchange sac, I was lucky enough to get to play one successfully in a game here on chess.com. Though there are mistakes in the early part of the game, it is largely left unannotated until we get to the sacrifice.
Here is the mate in 5 puzzle: