Bitcoin is a digital currency. Like other currencies, you can use it to buy things from merchants that accept it, such as Overstock.com, or, as is more often the case, hold on to it in hopes that it will increase in value. Unlike traditional currencies, which rely on governments and central banks, no single entity controls bitcoin. Rather, it is supervised by a worldwide network of volunteers who maintain computers running specialized software. As long as people run bitcoin software, the currency will keep working, because everything needed to keep it working is stored in a distributed ledger called the blockchain. And even though it's all digital, bitcoin is scarce.

Its most wild-eyed proponents believe bitcoin's decentralized, cryptographic approach to currency can yield a host of benefits: limiting central bankers’ ability to damage economies by printing too much money; eliminating credit-card fraud; bringing the unbanked masses into the modern economy; giving people in unstable economies a safe place to park their money; and making it cheap and easy to transfer funds. But bitcoin has yet to realize these goals, and critics argue it may never live up to the hype.

When you send or receive bitcoin, your bitcoin software, referred to as a “wallet,” records the transaction in the blockchain. The blockchain is maintained by, and distributed across, the roughly 200,000 computers running bitcoin software. If someone tries to alter the ledger to make it look like they have more bitcoin than they’re supposed to, the tampering will be apparent because it won't match the other copies of the blockchain.

People who commit the computing resources to processing bitcoin transactions are paid in bitcoin, but only if the computers they operate are first to complete complex cryptographic puzzles in a process called "mining.” New bitcoins are created automatically by the software and awarded to the winners of the race to solve these puzzles. As of February 2018, that award is 12.5 bitcoins. By design, only 21 million bitcoins will ever be created. Those who process transactions can also collect fees; the fees are optional and set by the person who initiates a transaction. The larger the fee, the faster the transaction will likely be completed. This system keeps bitcoin scarce while rewarding people for investing in the infrastructure required to keep a global payment-processing system running. But the mining process comes with a big catch: It uses an enormous amount of electricity.

Bitcoin is attracting more and more investors. In 2018, Goldman Sachs revealed that it plans to open a bitcoin trading unit, and the New York Stock Exchange is reportedly considering a bitcoin trading platform as well. But adoption of the cryptocurrency has been hobbled by a series of scandals, high-tech heists, and disputes over the software's design, all of which illustrate why financial regulations were created in the first place. The bitcoin community has solved some mind-boggling technological problems. But making bitcoin a true replacement for, or even adjunct to, the global financial system requires more than just great tech.

The History of Bitcoin

On Halloween 2008, someone using the name Satoshi Nakamoto sent an email to a crytography mailing list with a link to an academic paper about peer-to-peer currency. It didn't make much of a splash. Nakamoto was unknown in cryptography circles, and other cryptographers had proposed similar schemes before. Two months later, however, Nakamoto announced the first release of bitcoin software, proving it was more than just an idea. Anyone could download the software and start using it. And people did.