15,000, making multi-millionaires of some early investors. You can’t touch, panda pool mining bitcoin or smell it. No one owns or controls it.

15 billion fortune for its mystery creator. To its fans, it is a brilliant invention that will free mankind from the tyranny of corrupt banks. To its critics, it’s a huge hype on a par with 17th Century Tulip Mania that poses a terrifying threat to the financial system. Bitcoin Bonanza but were too afraid to ask. Bitcoins in a vast online computer ledger, which has an address that is identified by a string of digits and letters.

In practice, most Bitcoin holders have an online wallet, which functions like a real one, in that you can open it on your PC or smartphone and see how much of the currency you have. These wallets are protected by passwords and authentication codes. But who creates the Bitcoins and how? It sounds like a strange term but it’s not a bad analogy, because the current Bitcoin fever is a bit like the California gold rush of 1849.

Rather than brawny miners with picks and shovels looking for nuggets, Bitcoin miners are brainboxes hoping to strike virtual gold. When setting up Bitcoin, its creator decreed that only 21 million of them can ever be unearthed. The miners do this by using their computers to solve fiendishly difficult maths puzzles. Each time their computers come up with a correct answer, the prize is a Bitcoin. There are more than 16 million in existence now and the puzzles are getting harder and harder. I got an A in my maths O-level.