King

The king can move to any adjacent square, but only when that square is not occupied by a friendly piece or attacked by the opponent. This restriction applies even when moving the king would capture an attacking piece.

A player in check must remove the attack immediately. The king may move, the attacking piece may be captured, or the attack may be blocked when the checking piece attacks along a line. A move that leaves the king in check is illegal.

The two kings can never stand on adjacent squares because each king attacks every adjacent square.

The king usually reaches safety by castling rather than walking toward a corner one square at a time. Castling is a separate king move with extra conditions, so it should not be inferred from the king's normal movement rule.