Bitcoin's first real purchase was two pizzas, bought in 2010 for 10,000 coins — a sum later worth hundreds of millions of dollars.

Programmer Laszlo Hanyecz offered the coins to anyone who would order him pizza, and someone did, in what's now celebrated every year as 'Bitcoin Pizza Day.' At the time the coins were essentially worthless novelties; the transaction is remembered less as a bad deal than as the first proof that the currency could buy something real.