  The arena normally used in black holes thermodynamics was recently
generalized to incorporate a broad class of physically interesting situations.
The key idea is to replace the notion of stationary event horizons by that of
`isolated horizons.' Unlike event horizons, isolated horizons can be located in
a space-time quasi-locally. Furthermore, they need not be Killing horizons. In
particular, a space-time representing a black hole which is itself in
equilibrium, but whose exterior contains radiation, admits an isolated horizon.
In spite of this generality, the zeroth and first laws of black hole mechanics
extend to isolated horizons. Furthermore, by carrying out a systematic,
non-perturbative quantization, one can explore the quantum geometry of isolated
horizons and account for their entropy from statistical mechanical
considerations. After a general introduction to black hole thermodynamics as a
whole, these recent developments are briefly summarized.
