My research will focus on main philosophical accounts and formal theories of informal provability.I will argue that these theories struggle with some problems and do not have satisfactoryphilosophical motivations. The second aim of my research is to investigate the relation betweentheories of truth and the notion of informal provability. In order to avoid some of the philosophicaldifficulties encountered by previous theories, I will develop a theory of informal provabilityanalogous to Kripke's theory of truth.