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 is under attack, or a stalemate (a draw) if the king is not. Each chess piece has its own way of moving. In the diagrams, the dots mark the squares where the piece can move if there are no intervening piece(s) of either color. Once in every game, each king is allowed to make a special move, known as "castling". Castling consists of moving the king two squares along the first rank toward a rook (which is on the player's first rank) and then placing the rook on the last square that the king has just crossed. Castling is permissible