This review is concerned primarily with the electrophotographic systems currently in use, i.e., the electrodeless stored energy systems. First, the history of reproduction is traced from printing, through wet- and dry-chemical photography, to electrophotographic systems. The electrodeless system is defined and described in terms of the processing. Then, the light sensitive materials and processing are examined, and the characteristics of the material comprising the electrophotographic layer are related to the operational steps of charging and exposure. The principal development materials, dry powder, and liquid toners, are described on an electrochemical basis, and the toning mechanisms are reviewed. Finally, the principal applications and future trends of electrophotographic systems are outlined.