I will introduce F-theory as a strong coupling formulation of Type IIB string theory, which elegantly combines phenomenologically appealing features proper to different corners of the perturbative regime. I will discuss how to fully access the dynamics of F-theory via a chain of dualities from M-theory, and how, in this context, general 7-brane backgrounds are described by the geometry of elliptic fibrations. I will furthermore describe the way to recover open/closed type IIB string physics at weak coupling by constraining the shape of the F-theory compactification. I will finally review the basic ingredients of F-theory phenomenology, especially focusing on the description of fluxes and on their use in the context of GUT model building.