Game theory is a branch of applied mathematics that is used in the social sciences, most
notably in economics, as well as in biology (particularly evolutionary biology and ecology),
engineering, political science, international relations, computer science, and philosophy.
Game theory attempts to mathematically capture behavior in strategic situations, in which an
individual's success in making choices depends on the choices of others. While initially developed
to analyze competitions in which one individual does better at another's expense (zero sum games),
it has been expanded to treat a wide class of interactions, which are classified according to
several criteria. Today, "game theory is a sort of umbrella or 'unified field' theory for the
rational side of social science, where 'social' is interpreted broadly, to include human as
well as non-human players (computers, animals, plants)" (Aumann 1987).

The birth of the theory of games (or perhaps the birth announcement) was the paper of
von Neumann, “Zur Theorie der Gesellshaftsspiele,” Math. Annalen, 100 (1928), 295–300.
This paper contains the min-max theorem for zero-sum two-person games and the core of the
characteristic function treatment of games with three or more players.

The infant of 1929 appears full grown in the impressive volume of von
Neumann and Morgenstern, Theory of Games and Economic Behavior, Princeton, 1944, 2nd ed.
1947, 3rd ed. 1953. Here we find the economic interpretation given full justice.