Bitcoin, the first, most-traded, and best-known cryptocurrency. The digital currency was created by an anonymous computer programmer or group of programmers known as Satoshi Nakamoto in 2009. Owners of Bitcoins can use various websites to trade them for other cryptocurrencies or even physical currencies, such as U.S. dollars or euros, or can exchange them for goods and services from a number of vendors.
Nakamoto was concerned that traditional currencies were too reliant on the trustworthiness of banks to work properly. Nakamoto proposed a digital currency, Bitcoin, that could serve as a medium of exchange without relying on any financial institutions or governments. The proposal was made in October 2008 in a paper published on the Bitcoin website, which had been founded in August 2008.
Bitcoin relies on public-key cryptography, in which users have a public key that is available for everyone to see and a private key known only to their computers. In a Bitcoin transaction, users receiving Bitcoins send their public keys to users transferring the Bitcoins. Users transferring the coins sign with their private keys, and the transaction is then transmitted over the Bitcoin network. So that no Bitcoin can be spent more than once at the same time, the time and amount of each transaction is recorded in a ledger file that exists at each node of the network. The identities of the users remain relatively anonymous, but everyone can see that certain Bitcoins were transferred. Transactions are put together in groups called blocks. The blocks are organized in a chronological sequence called the blockchain. Blocks are added to the chain using a mathematical process that makes it extremely difficult for an individual user to hijack the blockchain. The blockchain technology that underpins Bitcoin has attracted considerable attention, even from skeptics of Bitcoin, as a basis for allowing trustworthy record-keeping and commerce without a central authority.
