In chess, "the exchange" refers to a situation in which a player trades a "minor piece" (i.e. a bishop or a knight) for a rook. Since rooks are considered to be more valuable than minor pieces, the player who lost the bishop or knight is said to be "up the exchange" and the player who lost the rook is said to be "down the exchange." When a player purposely offers up a rook in exchange for a knight or bishop to receive some other form of compensation, it is called an "exchange sacrifice."