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.
The debate may appear abstract, with little bearing on the hard-boiled world of finance, but it is attracting increasing interest from economists and lawyers

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