Services on the Berlin S-Bahn have been provided by the Prussian or German national railway company of the respective time, which means the Deutsche Reichsbahn-Gesellschaft after the First World War, the Deutsche Reichsbahn of the GDR (in both East and West Berlin) until 1993 (except West Berlin from 1984 to 1994, the BVG period) and Deutsche Bahn after its incorporation in 1994.