A zero-sum game is a situation in game theory where one participant's gain is exactly balanced by another participant's loss. In other words, the total benefit and loss among all players remains constant, meaning that the sum of gains and losses equals zero. This concept is often used in competitive scenarios, such as sports or gambling, where one player's success directly results in another player's failure. In a zero-sum game, strategies and outcomes are crucial for players to understand. Common examples include chess and poker, where each player's move affects the other's chances of winning. The idea helps analyze competitive behavior in economics, politics, and psychology, illustrating how resources are allocated in a fixed-sum environment.