S-Bahn

The S-Bahn (/ˈɛsbɑːn/ ^ⓘ ESS-bahn, German: [ˈɛsˌbaːn] ^ⓘ), lit. 'S-Railway ', 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 (lit. 'rapid train'), Stadtbahn (lit. 'city train', not to be confused with the present-day Stadtbahn) or Stadtschnellbahn (lit. 'rapid city train').

Similar systems in Austria and German-speaking Switzerland are known as S-Bahn as well. In Belgium, it is known as S-Trein (Flemish) or Train S (French). In Denmark, they are known as S-tog [ˈesˌtsʰɔˀw], and in the Czech Republic as Esko or S-lines. In Milan, they are known as Linee S.

S-Bahn is also a treated as a train category in several European countries.