|A promotion is a chess term which is given to the pawn that reaches the eighth square, becoming a queen, knight, bishop or rook. The term queening is often used to describe a promotion, since the powerful queen is usually the best piece to promote to. Promotions to knight can be quite useful depending on the situation. In practice, promoting to a bishop or rook usually makes no sense since the queen can do everything that either of them can, and the player gives away more information about his planned strategy to the opponent by not choosing a queen. These underpromotions normally only occur in the context of chess problems.|
The promotion is not limited to pieces that have been captured. Some finer chess sets (see Chess piece) have an extra queen of each color, should it be needed. If there is a promotion to a queen, and no queen is available, an upside-down rook is normally used to designate a queen.
The ability to promote is often the critical factor in end games and thus is an important consideration in in opening and middle game strategy. A "passed pawn" is one which has no enemy pawns directly in front of it or to either side. Such a pawn is very valuable and should be pushed forward at every possible opportunity. On the other hand, the player defending against the passed pawn does well to place a piece (particularly a bishop) directly in front of it to prevent it from moving. According to chess grandmaster Aron Nimzowitsch such a pawn must be blockaded ("kept under lock and key").