From the Q&A mailbox:

Question: Do you know about the Oyster Card that is sold for travel in London? How does it compare to the TravelCard that is also sold?

Answer: The Oyster Card is a convenient way of paying for London public transportation by loading a dollar (well, pound) amount onto a plastic 'smartcard' and having individual fares deducted by the electronic readers at tube stations and on buses and trains. A refundable deposit of £3 is required for each card. The TravelCard is a pass for the same transport but cost is determined by areas travelled and for a specific amount of time, but it is loaded on to the blue plastic Oyster card.

Though many sites encourage you to buy in advance, our experts say that’s not necessary as purchasing it in London is not that time-consuming. (The exception is if you are traveling with children eligible for free transport but need an Oyster photocard, which must be ordered in advance. Click here for more information about child policies.) There  is also a 'Visitor' version of the card but it does not allow loading of the TravelCard and must be reloaded in £10 and £15 increments but does have a lower deposit (£2). What you should choose depends on your length of stay and the amount of transport you will be using and where. In general, for visits to London of more than four days, and definitely for more than five, a seven-day Travelcard is a money and time saver - one purchase, then unlimited use for those days. However, the Oyster card will ‘cap’ fare deductions over the course of a day at the one-day Travelcard rate, so there’s no sense in buying the one-day TravelCard option. Visit this site for more information.

To submit your question to the AAA travel experts, click here.