In the 21st century, game theory applies to a wider range of behavioral relations, and it is now an umbrella term for the science of logical decision making in humans, animals, as well as computers. Traditional game theory addressed two-person zero-sum games, in which a participant's gains or losses are exactly balanced by the losses and gains of the other participant. It has applications in many fields of social science, used extensively in economics as well as in logic, systems science and computer science. Game theory is the study of mathematical models of strategic interactions among rational agents.