Oyster is a cashless payment system accepted on most public transport in Greater London. An Oyster card can store up to £90 in credit for pay-as-you-go, a travelcard season ticket and a National Rail discount card. It can be used on buses, trams, the tube, DLR and National Rail services. You can buy them
at tube stations, London Overground stations, some National Rail stations, Oyster Ticket Stops (shops). A £5 refundable deposit is required.
Each Oyster card communicates with Oyster readers (validators) when the card is touched
(placed flat) on the reader. The card does not have to physically touch the reader as it uses near-range wireless so can communicate though wallets and ticket holders.
On buses you must touch in on the bus when boarding, while on trams you must touch in on a station reader just before boarding. You must not touch out on either buses or trams. On the tube, DLR and National Rail you must touch in at the start of your journey and touch out at the end so that the correct fare can be charged. Where gates are in operation your card will open the gates if it is valid. If the gates are not in operation you must still touch in or out, either on the gates if they are locked open or on yellow validators which can be used either for entry or exit. A valid card will change the orange light to green along with one beep for an adult card or more than two beeps for a child card. If there is a problem then the light will change to red and you will get two beeps.
The Oyster system charges a price per journey. A single journey can consist of travel by either
a mix of National Rail, Underground, Overground and DLR, or
alternatively a single
other mode such as bus, provided that the gap between sections is reasonable.
Many thanks to MikeWh and his Oyster and National Rail
website for information used in this section.