Treballs Finals de Grau de Matemàtiques, Facultat de Matemàtiques, Universitat de Barcelona, Any: 2018, Director: Josep Vives i Santa Eulàlia[en] This work presents the transformation of Harsanyi, that help us to transform a game with incomplete information into a game with information complete but imperfect, and the basic results related to games with incomplete information. After a long introduction with examples, this report studies Bayesian games in depth and presents the notion of equilibrium in these cases.