The king is the most important piece in chess: the game is lost the moment your king is checkmated — attacked with no way to escape. It moves one square at a time in any direction (horizontally, vertically, or diagonally), making it slow but omnidirectional.
Its safety comes before everything else. In the opening, the king is dangerously exposed in the center and should seek shelter quickly through castling (kingside or queenside), tucking it behind its pawns and away from the active pieces fighting for the center.
In practice, the golden rule is straightforward: never neglect your king’s safety. A poorly sheltered king becomes a permanent target, forcing costly defensive moves every turn. In the endgame, however, the king transforms into an active piece. With fewer pieces on the board, it must advance to support its pawns or challenge the opposing king — a skill that is essential in king-and-pawn endings.