The touch-move rule in chess specifies that a player, having the move, who deliberately touches a piece on the board must move or capture that piece if it is legal to do so. If it is the player's piece that was touched, it must be moved if the piece has a legal move. If the opponent's piece was touched, it must be captured if it can be captured with a legal move. If the touched piece cannot be legally moved or captured, there is no penalty. This is a rule of chess that is enforced in all formal over-the-board competitions. A player claiming a touch-move violation must do so before themselves touching a piece. Online chess does not use the touch rule, letting players "pick up" a piece and then bring it back to the original square before selecting a different piece, and also allowing players to premove pieces while waiting for the opponent to move.

A player who wants to adjust a piece on its square without being required to move it can announce the French j'adoube ("I adjust") before touching the piece. While j'adoube is internationally understood, a local language equivalent such as "adjusting" is usually acceptable. A player may not touch the pieces on the board during the opponent's turn.

There is a separate rule that a player who lets go of a piece after making a legal move cannot retract the move.

These rules have the following consequences:

• Since moving a rook to next to its king is a valid rook move, it cannot be changed to a castling move by moving the king over it. Castling must be done by touching the king first, and the rook afterwards.
• The player who has released the king after moving it two squares on its home rank has not yet completed a move, but must complete the move by castling on that side, if legal. If that castling move is illegal, another legal king move must be played, if there is one. This may include castling on the other side.