In chess a passed pawn is a pawn that has no other pawns in directly in front of it, or in front of it on adjacent files. "Passed pawns must be pushed" is a popular saying in chess whose origins are unknown. It is also a sound strategic principle. "Pushing" a pawn means continually advancing it forward on the chessboard toward its queening square. Passed pawns become increasingly powerful and disruptive to the opponent's gameplay as they get closer to the queening square. A passed pawn that reaches the sixth or seventh rank becomes nigh unto an emergency and can lead to significant counterplay by its owner.