Abstract: Black holes are among the most interesting objects in our universe. Classically, black holes have remarkably simple descriptions, in terms of a small number of physical parameters. Quantum mechanically however, they are much more mysterious. In any complete quantum theory of gravity, black hole singularities must be resolved, and we must have a consistent description of black hole formation and evaporation. In this talk I will describe my recent work on the internal structure of black holes in string theory, and I will describe how this programme offers the potential of a complete and consistent quantum description of black hole physics.