Delve into the intricacies of black hole thermodynamics in this comprehensive lecture delivered by Robert Wald from the University of Chicago. As part of the ICTP School on Geometry and Gravity, this 79-minute talk explores advanced concepts in astrophysics and gravitational theory. Gain insights into the thermodynamic properties of black holes, building upon foundational knowledge from previous sessions. Examine the mathematical frameworks and physical principles that govern these enigmatic cosmic phenomena, and understand their significance in the broader context of modern physics and cosmology.