This book is the first to give a comprehensive view on the polaron and bipolaron theory of high-temperature superconductivity, one of the most significant discoveries in physics in the past decade. With the discovery of high-temperature superconductors, research into polarons and bipolarons has attracted much attention. They have also been observed previously in magnetic semiconductors and transition metal oxides. The thorough investigation of these non-superconducting materials has contributed greatly to the basic understanding of the physical properties of both polarons and bipolarons. This book will be of great interest to researchers in condensed matter physics, and especially those working in the field of superconductivity.