Devices that perform functions in the superconducting state that would be difficult or impossible to perform at room temperature, or that contain components which perform such functions. The superconducting state involves a loss of electrical resistance and occurs in many metals and alloys at temperatures near absolute zero. An enormous impetus was provided by the discovery in 1986 of a new class of ceramic, high-transition-temperature (T_c) superconductors, which has resulted in a new superconducting technology at liquid nitrogen temperature. Superconducting devices may be conveniently divided into two categories: small-scale thin-film devices, and large-scale devices which employ zero-resistance superconducting windings made of type II superconducting materials.