In a Nash Equilibrium, if one player can improve their outcome by changing their strategy while the others keep theirs unchanged, it signifies a stable equilibrium.

A Nash Equilibrium is a situation in a game where no player can gain an advantage by changing their strategy, as long as the other players keep their strategies the same. This means that every player's choice is the best they can do given what the others are doing. If one player can change their strategy and do better, it shows that the current situation is not stable, because players will want to change their strategies to improve their outcomes. For example, imagine two friends deciding whether to go to a movie or a concert. If one friend prefers the concert but the other is set on the movie, the current choice is not a Nash Equilibrium because the concert-goer can switch to the movie for a better experience.