Promotion happens when a pawn reaches the far end of the board and is immediately exchanged for a queen, rook, bishop, or knight of the same colour. Most players choose a queen because it is the strongest piece, but occasionally a knight, rook, or bishop is better — choosing something other than a queen is called underpromotion. You can end up with more than one queen this way. Promotion is why a single passed pawn can decide an endgame: pushing it to the last rank often wins the game outright. Guard and advance your passed pawns carefully.