‘Time’ outlines how strategies can be affected by timing. Strategies in chess or poker depend on when something happens, as well as what it is. These can be explained using payoff tables, but it is easier to use a tree analogy, with the moves of the game progressing from root to leaf. Backwards induction can be used to regress through a game from its final outcome to determine the best strategy to adopt. At each branch the dominated strategies (i.e. those which always yield poorer payoffs) are eliminated. In games with perfect information backwards induction leads to Nash equilibria in both the game as a whole and any subgames.