What is it?
A paper ticket that lets you travel as much as you like for 1 or 7 days.
How does it work?
You decide which zones (travel areas) you want to travel in and then purchase the correct Travelcard. It can then be used on any public transport in London.
Benefits
Simple: Once you have your ticket, you get unlimited travel for a full day or week. No need to use the ticket machines in the tube station or calculate how much credit you might need.