Nonlocal games are simple games which are used in quantum information to study the power of entanglement. Suppose the players perform well in the game. A basic question is: what does this tell us about the players' strategy? Any constraint on the strategy will hold for all devices that the players could use to play the game, a property known as device-independence. I will give an introduction to this subject from the perspective of C*-algebras and noncommutative geometry.