Questions relating to the King
In standard chess, the King is the most important piece; the object of the game being to trap it so that any allowable move made cannot remove it from attack by any opposing piece (such attack against the King is known as check - see check). The King may move one square per move in any direction - up, down, left, right, or diagonally, but it may not move into check, and it may not move to occupy a square already occupied by one of its own pieces. The exception to the one-square-per-move rule is castling (see castling). This is a limited circumstance in which the King may move two squares.
When the King is put into check, the attacked player must immediately, in the following move,
move the King out of check,
interpose a piece between the King and the attacking piece (if there is only one - in the case of a double check, this option is not possible), or
capture the attacking piece (again, if there is only one).
If none of these options is available, the King is checkmated (see checkmate), and the game is over.
The symbol for the King in most notations (see notation) is
For more information about the King, see the Wikipedia article.