The article by Robert M. Wald provides a comprehensive review of black hole thermodynamics, covering classical black hole mechanics, Hawking radiation, the generalized second law (GSL), and entropy bounds. The author discusses the mathematical resemblance between black hole mechanics and classical thermodynamics, highlighting the discovery of Hawking radiation, which allows for a consistent interpretation of black hole mechanics as ordinary thermodynamics. The GSL links black hole mechanics to classical thermodynamics, suggesting that the sum of the entropy of matter outside the black hole and a multiple of the black hole's area never decreases. The article also explores the identification of the area of the event horizon as the physical entropy of the black hole and the unresolved issues, such as the black hole information paradox and the degrees of freedom responsible for black hole entropy. The review concludes with a discussion of the robustness of the Hawking effect and the Unruh effect, and the validity of the GSL in various scenarios.The article by Robert M. Wald provides a comprehensive review of black hole thermodynamics, covering classical black hole mechanics, Hawking radiation, the generalized second law (GSL), and entropy bounds. The author discusses the mathematical resemblance between black hole mechanics and classical thermodynamics, highlighting the discovery of Hawking radiation, which allows for a consistent interpretation of black hole mechanics as ordinary thermodynamics. The GSL links black hole mechanics to classical thermodynamics, suggesting that the sum of the entropy of matter outside the black hole and a multiple of the black hole's area never decreases. The article also explores the identification of the area of the event horizon as the physical entropy of the black hole and the unresolved issues, such as the black hole information paradox and the degrees of freedom responsible for black hole entropy. The review concludes with a discussion of the robustness of the Hawking effect and the Unruh effect, and the validity of the GSL in various scenarios.