**Game theory** is the study of the structure and the rational strategies for performing in games or gamelike human interactions.

A key concept of game theory is the Nash Equilibrim. If all players have chosen a strategy and no player can benefit from changing their strategy unless other players also change their strategy, we are in a Nash equilibrium.

As an illustration, consider the problem known as "the prisoner's dilemma." Two suspects face imprisonment, but can get a reduced sentence by betraying each other. However, if neither of them betrays each other, they get a shorter sentence than if both do....