Promotion is a chess rule describing the transformation of a pawn that reaches its eighth rank into the player's choice of a queen, knight, rook, or bishop of the same color. The new piece replaces the pawn on the same square and is part of the move. Promotion is not limited to pieces that have already been captured. Every pawn that reaches its eighth rank must be promoted. Pawn promotion often decides the result of a chess endgame.
Since the queen is the most powerful piece, the vast majority of promotions in practical play are to a queen. Promotion to a queen is often referred to as queening. A promotion to a piece other than the queen is called underpromotion