Pin (chess) Pin (chess) In chess, a pin is a situation brought on by an attacking piece in which a defending piece cannot move without exposing a more valuable defending piece on its other side to capture by the attacking piece. Moving the attacking piece to bring on the pin is called pinning; the defending piece so restricted is described as pinned. Only pieces that can move an indefinite number of squares in a horizontal, vertical, or diagonal line (i.e. bishops, rooks, and queens) can pin. Kings, knights, and pawns cannot pin. Any piece can be pinned except the king, since the
Chess piece play, pieces of the Staunton chess set design are standard. The height of the king should be between . United States Chess Federation rules call for a king height between . A height of about is preferred by most players. The diameter of the king should be 40–50% of its height. The size of the other pieces should be in proportion to the king. The pieces should be well balanced such that their center of gravity is closer to the board. This is done by adding weights such as iron studs or lead blocks at the bottom and felted. It