Game theory is a study of strategic decision making. Specifically, it is "the study of mathematical models of conflict and cooperation between intelligent rational decision-makers", such that one participant’s choice of action is determined by taking into account all possible alternatives available to an opponent playing the same game. An alternative term suggested "as a more descriptive name for the discipline" is interactive decision theory.
The subject first addressed zero-sum games, such that one person's gains exactly equal net losses of the other participant or participants. This is because game theory has only been capable of analyzing very simple competitive situations. Thus, there is a great gap between what the theory can handle, and most actual competitive situations faced in real life.
Game theory is mainly used in economics, political science, military exercises, businesses, marketing and psychology, as well as logic, computer science, and biology.