So bitcoin’s a currency, right? Well, yes, it can be used to buy, sell and price goods much like dollars and euros.

A commodity? Come to think of it, it does behave a lot like oil and gold – it can be bought and sold in cash markets or via derivatives such as futures.

What about a security? Many cryptocurrencies are, in a way. They’re issued like stocks in “initial coin offerings” and used to represent shares in online projects...