Rapid transit in Germany consists of four U-Bahn systems and 14 S-Bahn systems. The U-Bahn, commonly understood to stand for Untergrundbahn, are conventional rapid transit systems that run mostly underground, while the S-Bahn or Stadtschnellbahn are commuter rail services, that may run underground in the city center and have metro-like characteristics in Munich, Hamburg and Berlin which they only have to a lesser extent in other cities. There are also over a dozen semi-metro or Stadtbahn systems that are rapid transit in the city center and light rail outside.

The S-Bahn is a hybrid urban-suburban rail system serving a metropolitan region predominantly in German-speaking countries. Some of the larger S-Bahn systems provide service similar to rapid transit systems, while smaller ones often resemble commuter or even regional rail systems. The name S-Bahn derives from Schnellbahn, Stadtbahn or Stadtschnellbahn.