You can use it to buy a pizza or pay a taxi fare, at least in theory. Simon Cox investigates the virtual currency Bitcoin. What is it, and who is buying and selling it?

You can use it to buy a pizza, or pay a taxi fare. Simon Cox looks at the virtual currency Bitcoin, which is exclusively online and independent of any government or company and where a user can be anonymous. In recent weeks, Bitcoin lost half its value due to a panic sell-off, but who are the people buying and selling this new currency and how does it work?