After its founding in 1920, the Deutsche Reichsbahn went its own way in the construction, procurement and modernization of steam locomotives and developed the concept of standard locomotives, which was recognized worldwide. At the same time, the largest transport company at the time continued to purchase well-known steam locomotive types from the state railway era that had proven their performance. All important information about the DR's steam locomotives from 1920 to 1945 is collected in this type compass.