High-temperature superconducting (HTS) thick films have undergone a period of rapid progress since their discovery in 1986. In this review thick-film materials are described with special reference to their processing, their properties and the development of devices. The devices include HTS magnetic shields, resonators for microwave filters, antennas and wire. The translation of science into applications has taken place in a relatively short time and already impressive performance is seen in HTS prototype devices.