THOM: I'd like to buy this please.

SHOPKEEPER: Ok, that's $20 thanks

SHOPKEEPER: What's this?

THOM: Oh, that's my currency. They're called Thom dollars.

SHOPKEEPER: What?

THOM: No, it's OK. One of these is worth $20 Australians dollars.

SHOPKEEPER: I don't think so

For the most part, shops in Australia are pretty strict on what sort of money they accept and trying to use something different won't get you very far. But in certain parts of the net a new type of money is trading hands and some are taking it pretty seriously. It's called bitcoin.

REPORTER: If you spend a lot of time online there's a chance you've come across this symbol before. There are quite a few online shops that accept bitcoin as a way of paying for the stuff you want.

UPSOT: Bitcoins are digital coins you can send through the internet

Bitcoin was invented in 2008 by a programmer who wanted to create a system of money that wasn't controlled by governments or banks. Together they play a big part in controlling the value of the money we use every day and if they make the wrong decisions a lot of people can suffer.

That's what we saw recently in Cyprus, when banks went broke and stopped people from getting to their money. With bitcoin there are no banks and Cyprus is one country where more and more people are using bitcoin as an alternative currency. So what exactly are bitcoins?

REPORTER: Hi Regan.

Regan Ware has been using bitcoins for years. He's so excited by the new type of money that he's started a group helping people in his local area to start using them.

REPORTER: So Regan, can you show me a bitcoin? What do they look like?

REGAN: I can't show them to you, they're not physical coins.

Regan explained that bitcoins exists as complicated computer codes which are stored and shared in virtual bitcoin wallets. They only exist on computers.

REPORTER: So how can you buy something with a currency that doesn't really exist?

REAGAN: That 20 dollars you're holding; how do you know it's worth $20?

REPORTER: It just is! See, it says so

REAGAN: It's worth 20 dollars because we've all agreed that it's worth $20. Actually it's just a piece of plastic that's not worth anything by itself. In fact anything can be used as currency.

But for a currency to work lots of people have to trust that it's worth something. It also has to be hard to copy. And just like our plastic notes, bitcoins are really hard to copy.

REGAN: You can't copy bitcoins they're actually a really large computer code and it actually takes a lot of computers to solve that.

But there is a down side. While the value of regular money is kept under fairly tight control how much bitcoins are worth depends on how many people want to buy them. In the past month the value of bitcoins has gone from about $40 to more than $250 then back down again and people have lost and gained a lot of money in the process.

Some financial experts reckon they could be just a fad and investing in them is not a good idea. There are also concerns that they're being used by criminals who want to trade in something that's harder to track than traditional money. But there are still plenty of bitcoin enthusiasts hoping that one day they'll be in everyone's virtual wallets

CUSTOMER: Do you accept bitcoin transfer.

SHOPKEEPER: Sure