Black hole horizons and the thermodynamics of strings

We review the classical thermodynamics and the greybody factors of general (rotating) non-extreme black holes and discuss universal features of their near-horizon geometry. We motivate a microscopic interpretation of general black holes that relates the thermodynamics of an effective string theory to the geometry of the black hole in the vicinity of both the outer and the inner event horizons. In this framework we interpret several near-extreme examples, the universal low-energy absorption cross-section, and the emission of higher partial waves from general black holes. (orig.)