Theory of Superconductivity: From Weak to Strong Coupling leads the reader from basic principles through detailed derivations and a description of the many interesting phenomena in conventional and high-temperature superconductors. The book describes physical properties of novel superconductors, in particular, the normal state, superconducting critical temperatures and critical fields, isotope effects, normal and superconducting gaps, tunneling, angle-resolved photoemission, stripes, and symmetries. The book divides naturally into two parts. Part I introduces the phenomenology of superconductivity, the microscopic BCS theory, and its extension to the intermediate coupling regime. The first three chapters of this part cover generally accepted themes in the conventional theory of superconductivity and serve as a good introduction to the subject. Chapter 4 describes what happens to the conventional theory when the coupling between electrons becomes strong. Part II describes key physical properties of high-temperature superconductors and their theoretical interpretation. Alternative viewpoints are discussed, but the emphasis is placed on the bipolaron theory.