In chess, the exchange is the material difference of a rook for a minor piece (i.e. a bishop or knight). Having a rook for a minor piece is generally advantageous, since the rook is usually more valuable. A player who has a rook for a minor piece is said to be up the exchange, and the other player is down the exchange. A player who wins a rook for a minor piece is said to have won the exchange, while the other player has lost the exchange. The opposing captures often happen on consecutive moves, but this is not strictly necessary. Although it is generally detrimental to lose the exchange, one may occasionally find reason to purposely do so; the result is an exchange sacrifice.
"The exchange" differs from the more general "exchange" or "an exchange", which refers to the loss and subsequent gain of arbitrary pieces; for example, to "exchange queens" would mean that each side's queen is captured.[1]
The minor exchange is the exchange of a bishop for a knight. This term is rarely used.