This modern introduction to the physics of superconductors was edited by Paul Müller, (Walter Schottky Award for Solid-state Research) and Alexey V. Ustinov, both at the University of Erlangen. The revised and enlarged text is based on a lecture course given by V.V. Schmidt at the Moscow Institute of Steel and Alloys. It provides a modern treatment of the physics of superconductors with special attention paid to the physical interpretation of the phenomena. This English edition has been enlarged by the inclusion of such new developments as high-temperature superconductivity, and, as such, is the most up-to-date textbook available on the subject. Numerous problems with solutions help the student to become familiar with this field.