S-Bahn

S-Bahn (/ˈɛsbɑːn/ ^ⓘ ESS-bahn, German: [ˈɛsˌbaːn] ^ⓘ; lit. 'S-train') is a type of hybrid commuter rail and rapid transit service, originating in German-speaking countries. In general, S-Bahn systems link suburbs with the city centre at moderate speeds, while continuing across the urban core over a central high-frequency corridor where multiple lines converge, where they provide a rapid means of travel across the city. The name S-Bahn derives from the German terms Schnellbahn (lit. 'rapid train'), Stadtschnellbahn (lit. 'rapid city train'), and Stadtbahn (lit. 'city train'; not to be confused with the modern Stadtbahn).

The first such network, the Berlin S-Bahn, began operation in December 1930 and inspired similar systems across Europe. The term "S-Bahn" has since become a generic term for hybrid suburban–urban rail networks, with counterparts such as the S‑tog in Denmark, S‑Trein/Train S in Belgium, Esko/S‑lines in the Czech Republic, Linee S in Italy, and SKM in Poland. The S-Bahn is also recognized as a train category in several European countries. The concept also influenced systems outside the German-speaking world, including the Réseau Express Régional (RER) in Paris and its counterparts in other cities.