The present book aims at describing the phenomenon of superconductivity and high-temperature superconductors discovered by Bednorz and Muller in 1986. The book covers the superconductivity phenomenon, structure of high-Tc superconductors, critical currents, synthesis routes for high Tc materials,  superconductivity in cuprates, the proximity effect and SQUIDs, theories of superconductivity and applications of superconductors.