Superconductivity. Introduction and overview. Magnetism and currents in superconductors. Refrigeration. Industrial applications. Sensitive applications. Basic concepts of theory of superconductivity. The new superconductors. High temperature superconductivity (HTSC) basic principles. structure. Phase diagrams and equilibrium. Effects of doping. Mechanical properties. HTSC theory. Weak links. Carrying electricity. Flux line motion and flux pinning. Processing methods. HTSC wire. Protecting against damage. AC losses. Electric power applications of HTSC. Transmission lines. Levitation. Superconducting magnetic energy storage. Electric machinery. Fault current limiters. Future possibilities. New refrigerators. Applications to measurement and process control. High magnetic fields. Organic superconductors. Aerospace applications.