Game theory is the formal study of conflict and cooperation between interdependent decision-makers. It has applications in economics, political science, military strategy, biology, and computer science. Key concepts in game theory include Nash equilibrium, where no player can benefit by changing their strategy alone, and mixed strategies, where players randomize between pure strategies. Zero-sum games model situations where one player's gains equal the other's losses. The presentation provides an example game modeling competition between two firms, which has a pure strategy Nash equilibrium given by the saddle point value in the payoff matrix.