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Urban rail transit is a general term，which usually refers to electric-powered，wheel-rail public transportation with higher capacity and speed.It usually includes subways，light rails and trams.Unlike buses or trams，urban rail transit systems are electric railways that operate on an exclusive right-of-way，which cannot be accessed by pedestrians or other vehicles of any sort，and which is often grade separated in tunnels or on elevated railways.

Modern services on urban rail transit systems are provided on designated lines between stations typically using electric multiple units on rail tracks，although some systems use guided rubber tyres，magnetic levitation，or monorail.The stations typically have high platforms，without steps inside the trains，requiring custom-made trains in order to avoid gaps.They are typically integrated with other public transport and often operated by the same public transport authorities.However，some urban rail transit systems have at-grade intersections between a rapid transit line and a road or between two rapid transit lines.It is unchallenged in its ability to transport large numbers of people quickly over short distances with little use of land.Variations of urban rail transit include people movers，small-scale light metro，and the commuter rail hybrid S-Bahn.

The world's first urban rail transit system was the partially underground Metropolitan Railway which opened as a conventional railway in 1863，and now forms part of the London Underground.In 1868，New York opened the elevated West Side and Yonkers Patent Railway，initially a cable-hauled line using static steam engines.

The world's largest urban rail transit network is the Greater Tokyo rail system with more than 40 million daily passengers and 882 stations within the metropolis.

The world's largest single urban rail transit service provider by both length of track[842 miles（1，355 km），including non-revenue track]and number of stations（469 stations in total）is the New York City Subway.By length of passenger route，the world's longest singleoperator urban rail transit system is the Shanghai Metro.The busiest urban rail transit systems in the world by annual ridership are the Tokyo subway system，the Seoul Metropolitan Subway，the Moscow Metro，the Beijing Subway，and the Shanghai Metro.