A rook (♖ ♜ borrowed from Persian رخ, rokh) is a piece in the strategy board game of chess. Formerly the piece was called the tower, marquess, rector, and comes (Sunnucks 1970). The term castle is considered informal, incorrect, or old-fashioned. However, in Persian the word for "castling" is qal'eh raften (from qal'eh, "castle") and not rokh raftan.
Each player starts the game with two rooks, one in each of the corner squares on their own side of the board.
In algebraic notation, the white rooks start on squares a1 and h1, while the black rooks start on a8 and h8. The rook moves horizontally or vertically, through any number of unoccupied squares (see diagram). As with captures by other pieces, the rook captures by occupying the square on which the enemy piece sits. The rook also participates, with the king, in a special move called castling.