The book "Functional Analysis, Sobolev Spaces and Partial Differential Equations" by Haim Brezis is a thoroughly revised and expanded English edition of the significant work on functional analysis. It provides a clear and coherent presentation of the essential results of functional analysis in connection with the main results of the theory of partial differential equations (PDEs). This unique combination makes the book a valuable resource for students and professionals engaged with these closely related topics. In addition to the theoretical foundation, the book includes a variety of problems and exercises, complete with solutions, to deepen understanding. The English edition complements the existing translations in several languages and represents a welcome addition to the literature in this field.