King (chess)

The King (♔♚) is the most important piece in the game of chess. The king represents the prize the opposition seeks to win. If a player's king is threatened and cannot escape capture, the king is said to be in checkmate, and the player which owns that king loses the game. In a conventional game of chess, White starts with the king in the middle-right of their first rank (between the queen and the king-side bishop). Black starts with the king directly across from the white king. In algebraic notation, the white king starts on e1 and the black king on e8.

Movement

A king can move one square in any direction (horizontally, vertically, or diagonally). The distance it can move is known as the Chebyshev distance. The exception to this rule is that it may not move onto a square that is threatened by an enemy piece. As with most pieces, it captures by moving onto a square occupied by an enemy piece.

Castling

In conjunction with a rook, the king may make a special move called castling. Castling consists of moving the king two squares towards either one of the original rooks, then moving the rook onto the square over which the king crossed.

Check and checkmate

If a player's move places the opponent's king under attack, that king is said to be in check, and the player in check is required to immediately remedy the situation. There are three possible methods to remove the king from check:

Physically moving the king to an adjacent non-threatened square
Interposing a piece between the king in check and the attacking piece (in order to break the line of threat)
Capturing the attacking piece

If none of these three options are possible, the player's king has been checkmated and the player loses the game.

Stalemate

A stalemate occurs under a specific set of circumstances:

The king is not in check
The player has no legal moves

If this happens, the king is said to have been stalemated and the game ends in a draw. A player who has very little or no chance of winning will often try to place the king in stalemate in order to avoid a loss.

Role in gameplay

In the opening and middlegame, the king will rarely play an active role in the development of an offensive or defensive position. Instead, a player will normally try to castle and seek safety on the edge of the board behind friendly pawns. In the endgame, however, the king emerges to play an active role as an offensive piece as well as assisting in the promotion of their remaining pawns.

It is difficult to assign a value to the king relative to the other pieces, as it cannot be captured or exchanged. In this sense, its value is infinite. But as an assessment of the king's capability as an offensive piece in the endgame, it is often considered to be slightly stronger than a bishop or knight -- Lasker in Lasker's Chess Primer gave it the value of a knight and a pawn.

External links

Piececlopedia: King by Hans L. Bodlaender and Fergus Duniho.

Chess pieces