It’s a currency without a country.

Bitcoins, a novel form of Internet cash, have shot up in value over the last six months and are spawning a host of startups that act as exchanges for people buying, selling or transferring the stateless cyber-currency, which isn’t tied to any central bank or US government regulator.

The technology offers rewards and risks for users and investors. Retailers who accept bitcoins offer lower prices than those that rely on credit cards to process transactions, and buying and holding onto bitcoins has paid off for some investors. Two years ago, bitcoins were worth about a dollar. Now they hover around $72.

Charlie Shrem, CEO of Bitinstant, a bitcoin-exchange startup based in New York, says the digital doubloons are used by investors (both long-term and day traders), as well as people who want to make overseas transactions or send money back home to foreign countries without the hassle and cost of wire transfers.

For investors, the mathematics behind bitcoins ensure that there can only ever be 21 million of them, putting a cap on inflation. There are about 10 million in circulation right now, with a reported total value of around $740 million.