Null move

In game theory, a null move is a decision by a player to "pass" (that is, not to make a move) when it is their turn to move. Even though null moves are against the rules of many games, they are often useful to consider when analyzing these games. Examples of this include the analysis of zugzwang in chess, and the null-move heuristic in game tree analysis.

Null moves are also an important element in the construction of combinatorial game theory.