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 Hertfordshire, with 113 stations on the six lines that make up the network.
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 (TfL). Operation has been contracted to Arriva Rail London since 2016. TfL previously assigned orange as a mode-specific colour for the Overground in branding and publicity including the roundel, on the Tube map, trains and stations.
In 2024, each of the six Overground lines were given distinct colours and names – Lioness, Mildmay, Windrush, Weaver, Suffragette, and Liberty – which are intended to reference London's diverse history and communities.