Move

A move is the action taken by one player on a turn. White makes the first move, and the players then alternate. The move must be legal: it must follow the piece's movement rules and may not leave the player's own king under attack.

In ordinary use, one move is one individual action. In algebraic notation, the written system that identifies pieces and squares, one move number commonly groups White's move and Black's reply. This is why “move 20” may refer to the numbered pair even though each player performed a separate action.

A move made and a move completed

In over-the-board play, a move is generally considered made when the player releases the piece on its destination square and completes any capture. When a chess clock is used, the move is normally completed by pressing the clock, which stops the player's time and starts the opponent's. If the move ends the game, pressing the clock is not required for the result to exist.

Rules that count moves specify whose moves are counted. The fifty-move rule, for example, requires 50 moves by each player, not 50 combined actions.