A bow and an apology: Mark Karpeles, CEO of Mt. Gox, was contrite at the start of a news conference in Tokyo on Friday in which it was announced that the firm has filed for bankruptcy. Kyodo/Reuters/Landov hide caption
No, these aren't real bitcoins (just Bitcoin buttons). Fans of the virtual currency see several real benefits, including the elimination of fees for transferring money. Frank Jordans/AP hide caption
Bitcoin isn't just for shady business — it can also buy you some delicious goodness. The Old Fitzroy pub in Sydney is one of many food and drink businesses beginning to accept bitcoins as a valid method of payment. Cameron Spencer/Getty Images hide caption
Cameron (left) and Tyler Winklevoss testified Wednesday at a hearing about virtual currencies held by the New York Department of Financial Services. Craig Ruttle/AP hide caption
The world's first Bitcoin ATM opened at a Canadian coffee shop in Vancouver last year. But, Bitcoin use is far from mainstream at the moment. David Ryder/Getty Images hide caption
How low will they go? Jens Kalaene /DPA/LANDOV hide caption
Chinese banks cannot trade in Bitcoins, the digital currency that doesn't recognize international boundaries, China's top regulators said Thursday. Rick Bowmer/AP hide caption
A Welsh man has realized that he threw out a stash of Bitcoins along with an old computer hard drive. At an exchange rate hit today, they would be worth around $7.5 million. Here, a photo of tokens representing Bitcoins. Rick Bowmer/ASP hide caption
Economists say small-business owners — especially farmers dealing in high volume and low profit margins — are more likely to accept a volatile currency like Bitcoin than bigger businesses. Allen Sheffield/Flickr hide caption
A screen grab from a December 2012 StoryCorps interview with Ross Ulbricht, the alleged mastermind of the online marketplace known as Silk Road. YouTube hide caption
A chart shows the sharp rise of bitcoin against the U.S. dollar in the past five days. Only two months after exchange rates put a single bitcoin's value at around $20, it surpassed $200 Tuesday. Bitcoin Charts hide caption
An image depicts the SatoshiDice website, which exclusively uses Bitcoin, not dollars, for gambling. NPR hide caption

