Game Theory is essentially a discipline or a method of strategic thinking where the players will have to make decisions by looking from different perspectives, basically putting themselves in the shoes of the other players and anticipating their possible actions and reactions. The results of playing out these scenarios will be used to make decisions or choices.
When used in the context of business, Game Theory is most often used by business managers to figure out what their collaborators and competitors are thinking or planning.
It has become a very powerful tool for predicting the outcomes or results of interactions or transactions among a group of players or competitors, where the action of one will have direct effects or impact on the others, and the others will react according to those actions.