The Oyster card is a form of electronic ticketing used on public transport services within London. It is promoted by Transport for London and is valid on a number of different travel systems across London including London Underground, buses, the Docklands Light Railway (DLR), London Overground, trams, some river boat services and most National Rail services within the London Fare Zones. More importantly, it is very similar to Travelcard, a branch from the original London's e-payment cards.