Clear and easy to use
Let it be said: transportation in London is terrible. The prices are incredibly high and, during a holiday, it is unfortunately difficult to do without. To compensate, however, the city is very well serviced by metro, buses and planes. The metro lines are clear and easy to use. So the most economical solution for a stay of 4 days or less is to buy a day ticket which offers unlimited travel. The ticket costs 6 pounds and 60 cents and allows you to travel starting at 9:30 in the morning in zones 1 and 2 which is usually more than what you'll need. For a stay of more than 4 days, the transaction is a little more complex but far more economical. You have to go to a counter and ask for an "Oyster Card" which is a small plastic card that costs £5 and on which you can load different packages. The best is the "7 day travel card" for 27 pounds and 50 cents which provides unlimited travel for a week in zones one and two. At the end of the stay, you get the £5 deposit back. With the Oyster, if you need to go beyond zone 2 (which is rare for a short stay), just add a little more than a pound at the entrances of the stations.