What is the fewest move a person has to make to win a game of chess?

Technically, you opponent can give up whenever they want to, but the fastest checkmate possible is in two moves: Whites moves his (or her) kingside bishop pawn one or two spaces, Black moves his king's pawn one or two spaces, White moves his Kingside knight's pawn up two spaces, and black does queen to H4, checkmate, black wins.