London Overground (also known simply as the Overground) is a suburban rail network serving London and its environs. Established in 2007 to take over Silverlink Metro routes, it now serves a large part of Greater London as well as the home county of Hertfordshire, with 112 stations on nine different routes.

The Overground forms part of the United Kingdom's National Rail network but it is under the concession control and branding of Transport for London. Operation has been contracted to Arriva Rail London since 2016. TfL assigned orange as a mode-specific colour for the Overground in branding and publicity including the roundel, on the Tube map, trains and stations.

The overground looks like a loop line around greater London, however this is made up of separate lines as shown below.

Depots: Highbury & Islington to New Cross, Clapham Junction, Crystal Palace and West Croydon services are served by New Cross Gate TMD.

Richmond and Clapham Junction to Stratford, Watford Junction to Euston, and Gospel Oak to Barking services are served by Willesden TMD.

London Liverpool Street to Enfield Town, Cheshunt and Chingford, and Romford to Upminster are served by Ilford EMU Depot, Chingford sidings and Gidea Park Sidings.