Delve into the fascinating realm of black hole thermodynamics in this comprehensive lecture delivered by renowned physicist Robert Wald from the University of Chicago. As part of the ICTP School on Geometry and Gravity, explore the fundamental principles and cutting-edge concepts that govern the behavior of these enigmatic cosmic phenomena. Over the course of 73 minutes, gain valuable insights into the thermodynamic properties of black holes, their relationship to gravity and spacetime, and the implications for our understanding of the universe. Engage with complex mathematical and physical theories as Professor Wald expertly guides you through this captivating topic, laying the groundwork for further exploration in subsequent lectures.