The Oyster card is a payment method for public transport in London and some surrounding areas. A standard Oyster card is a blue credit-card-sized stored-value contactless smart card. It is promoted by Transport for London (TfL) and can be used as part of London's integrated transport network on travel modes including London Buses, London Underground, the Docklands Light Railway (DLR), London Overground, Tramlink, some river boat services, and most National Rail services within the London fare zones. Since its introduction in June 2003, more than 86 million cards have been used.
Oyster cards can hold period tickets, travel permits and, most commonly, credit for travel ("Pay as you go"), which must be added to the card before travel. Passengers touch it on an electronic reader when entering – and in some cases when leaving – the transport system in order to validate it, and where relevant, deduct funds from the stored credit. Cards may be "topped-up" by continuous payment authority, by online purchase, at credit card terminals or by cash, the latter two methods are available at stations and convenience stores. The card is designed to reduce the number of transactions at ticket offices and the number of paper tickets. Cash payment has not been accepted on London buses since 2014.
