The knight is a piece in the game of chess, representing a knight (armoured soldier) and often depicted as a horse's head. Each player starts with two knights on his home rank. In algebraic notation the white knights start on b1 and g1, while the black knights start on b8 and g8.
The knight move is unusual among chess pieces. It plays and captures alternately on White and Black squares; each move may be described as stepping one square horizontally or vertically and then one square diagonally away from the direction of the original square. See the diagram to the left for the eight legal moves of centralized knight. Unlike other chess pieces, the knight ignores any pieces in the path of its move, "jumping" directly to the destination square. Like most other pieces, it captures an enemy piece on its destination square.
The knight is the only piece that can move at the beginning of the game before any pawn move has been made. Because the best square for the initial move of each knight is fairly obvious and immediately available (b1-c3, g1-f3, b8-c6, and g8-f6), knights are on average brought into play slightly sooner than bishops, and much sooner than the rooks and the queen.
Note that the knight is the only piece that can be in position to attack a queen without being in the queen's line of attack. It is also not attacked by a king, bishop, or rook which it attacks. These features make the knight especially well-suited for executing a fork.
A knight is approximately equal in strength to a bishop. The latter's range is larger but the knight has the advantage of being able to reach any square of the board regardless of color. Since the knight is capable of jumping over obstructing pieces, it is considered to be more valuable earlier in the game when the board is more crowded. Also a crowded board provides more opportunity for the knight to execute forks. Once the board becomes more sparsely populated by pieces as they are captured the knight's value is diminished and the bishop's value is enhanced.
Most pieces are more powerful if placed near the center of the board, but for a knight this is particularly true. A knight on the edge of the board attacks only four squares, and a knight in the corner only two. Moreover, it takes more moves for a decentralized knight to switch operation to the opposite side of the board than a decentralized bishop, rook, or queen. For this reason the phrase, "A knight on the rim is grim," was coined.
Enemy pawns are very effective at harassing knights, because a pawn attacking a knight is not itself attacked by the knight. For this reason, a knight is most effective when placed in a "hole" in the enemy position, i.e. a square which can't be attacked by enemy pawns. In the diagram at right, white's knight on d5 is very powerful, more powerful than black's bishop on g7.
See also: Knight's Tour