Nash equilibrium is a concept within game theory where the optimal outcome of a game is where there is no incentive to deviate from the initial strategy. More specifically, the Nash equilibrium is a concept of game theory where the optimal outcome of a game is one where no player has an incentive to deviate from their chosen strategy after considering an opponent’s choice.

A needlessly sexist recreation of this concept in “A beautiful mind”: https://www.youtube.com/watch?v=2d_dtTZQyUM