Developed and studied extensively by many scholars since the 1950s, Game Theory is “the study of mathematical models of conflict and cooperation between intelligent rational decision-makers.”
Game theory provides a tool for analyzing the structure of potential actions and resulting payoffs for various players involved in interactive situations. So game theory enables you (a player/participant) to understand how the implications of your actions affect your competitors’ positions, and thus what their likely responses to your actions will be. In this way, game theory enables you to better understand―and thus better optimize―moves and countermoves by you and your competitors over time as you navigate within a dynamic market environment.
 Myerson, Roger B. (1991). Game Theory: Analysis of Conflict, Harvard University Press, p. 1. Chapter-preview links, pp. vii–xi.