Game theory is a branch of mathematics that tries to predict how players in a game are likely to act, with surprising applications in business and even social and political strategies. The theory is a systematic, formal way of analysing and solving the various choices and dilemmas companies and individuals often face in life, whether they are a mobile phone executive deciding what price to put on a new hand set, or a group of boys in a pub trying to decide how to approach the group of brunettes and a single blond at another table.

The most famous example of a game, and one to which John Nash contributed a major insight, is known as the prisoner's dilemma. The police arrest two criminals who then, individually, face a choice of informing on the other in exchange for a lighter sentence, or saying nothing in the hope the other prisoner will also say nothing, and potentially both getting off.