The currency is not yet officially legal in the United States but a handful of companies have been able to operate businesses based on bitcoin, earning money from the digital currency through advertising and other sources.

A new startup, the Winklevoss twins, are currently in the process of applying for a US$1 billion dollar funding round led by Sequoia Capital.

“We are very excited to work with the Winklovitz family to further their partnership with bitcoin, one of the most important and innovative technologies of our time,” said CEO Brian Armstrong.

There are about 4,500 bitcoins in circulation in the world and they are being traded on the bitcoin market through bitcoin exchanges such as BTC-e and Mt.

Gox.

The US has the highest number of bitcoins per capita in the OECD with more than $5,000 in digital currencies.

The value of bitcoins is now worth more than £6.2 billion ($8.1 billion) according to CoinDesk, although that is expected to rise in the coming years.

According to Armstrong, bitcoin is a tool that is going to be used by millions of people around the world.

“When you think about it, bitcoin can be a tool to make a lot of money for a lot more people,” Armstrong said.

As well as being a currency, bitcoins are also used for online shopping, peer-to-peer payments and in other ways to make money.