The theory of breeder reactors in relationship to a discussion of fission is presented. Different kinds of reactors are characterized by the cooling fluids used, such as liquid metal, gas, and molten salt. The historical development of breeder reactors over the past twenty-five years includes specific examples of reactors. The location and a brief description of various reactors and programs in the United States and foreign countries indicates a large expansion of such facilities in the near future. Lists of relevant reading topics and of motion pictures are included. (TS)