While taking a car is an everyday thing for most people in the US, it's not as common in the UK. When visiting London you may occasionally take a taxi, you'll certainly do a lot of walking, and you'll definitely want to use the London Underground, or the tube.
The tube is an underground network of trains that can take you pretty much anywhere in the city. There are stations all over. Just look for this sign.
There are many options when buying tickets; what you get may just depend on how long you are staying for. You can purchase tickets by the day and depending on what lines you are going to take, or you can buy what is called an Oyster card. The Oyster card is a blue, plastic card you can add credit to and pay as you go. This may be a better option if you are staying for a longer period of time.
There are usually maps at each station to help you find what stops you need and which line to take to get to your final destination.
To check out prices and get a tube map, check out the Transport for London website.
The tube wasn't always just used for travel. During World War II, London subway stations were used as shelters during bombing raids. This past weekend, Aldwych station was opened to the public to mark the 70th anniversary of the Blitz. Staff dressed in period clothing and walked visitors around the station. Tickets sold out before the event even started. You can read the whole story from the Associated press here.Whether getting from one point to another or commemorating events of London past, the tube is great resource to anyone visiting London.