MATT: Welcome to the world's newest and most exciting currency, set to revolutionise money as we know it. Introducing Mattcoin. Any questions?

RUBY: I have a question.

MATT: Yes, you in the front there.

RUBY: What is it?

MATT: Uh, well, as you can see, it's a coin with my face on it.

RUBY: Yes, but how does it work?

MATT: How does it work? Yes.

OK, you need a bit more than a fancy logo and a very impressive, well-respected, name, to create your own currency. But in recent years, lots of people really have created their very own money. Currencies that only exist in virtual form, but can be used and transferred around the world. And the biggest, and most well-known, is bitcoin.

Bitcoin was invented in 2008 by a programmer who wanted to create a system of money not controlled by governments or banks. Bitcoin works, in theory, like an online version of cash. You can use it to buy products and services, although unlike the Aussie dollar, not many shops accept bitcoin yet.

Each bitcoin is basically a computer file which is stored in a 'digital wallet' app on a smartphone or computer. People can send bitcoins (or part of one) to your digital wallet, and you can send bitcoins to other people. Every single transaction is recorded in a public list called a blockchain. This makes it possible to trace the history of bitcoins to stop people from spending coins they don't own, or making copies of them.

RUBY: So where can I get it?

MATT: Ah, yes.

You can buy cryptocurrencies, like bitcoin, with normal money or create them using a computer. That's called mining. The computers are made to work out incredibly difficult sums, and occasionally they are rewarded with a coin for the owner to keep. It's a lot more complicated than it sounds.

But while lots of people have got behind it, there is a down side. While the value of regular money is kept under fairly tight control how much cryptocurrencies, like bitcoin, are worth depends on how many people want to buy them at that exact moment. And that's what all the fuss has been over recently. The price of bitcoin spiked hugely towards the end of last year, but has been dropping ever since. It means people who got in really early have seen an incredible return on their investment. But some, who bought bitcoin later, have actually lost a lot of money.

RUBY: So why should I buy Mattcoin?

MATT: Yeah, you should definitely buy Mattcoin.

It's a good question. Although it's not always stable, some people like that cryptocurrencies aren't regulated by governments. But there are concerns they can be used by criminals who want something that's harder to track than traditional money.

Bitcoin's even been banned in some countries. But despite that uncertainty, cryptocurrencies still have a lot of supporters. And while some virtual currencies have come and gone, others seem like they're here to stay.

MATT: So, who wants Mattcoin?