Bitcoin is a cryptocurrency and worldwide payment system. It is the first decentralized digital currency, as the system works without a central bank or single administrator. The network is peer-to-peer and transactions take place between users directly, without an intermediary.

These transactions are verified by network nodes through the use of cryptography and recorded in a public distributed ledger called a blockchain. Bitcoin was invented by an unknown person or group of people under the name Satoshi Nakamoto and released as open-source software in 2009.

Bitcoins are created as a reward for a process known as mining. They can be exchanged for other currencies, products, and services. As of February 2015, over 100,000 merchants and vendors accepted bitcoin as payment. Bitcoin can also be held as an investment.

According to research produced by Cambridge University in 2017, there are 2.9 to 5.8 million unique users using a cryptocurrency wallet, most of them using bitcoin.

The first bitcoin transaction took place on January 12, 2009, from creator Satoshi Nakamoto to developer Hal Finney. Nakamoto subsequently disappeared from any involvement in bitcoin.

Andresen later became lead developer at the Bitcoin Foundation. This foundation was established in September 2012 to promote bitcoin’s development and uptake.

In May 2013, US government seized assets associated with Silk Road, an online black market that facilitated the sale of illegal drugs; and in October 2013 the US FBI shut down the Silk Road online marketplace, causing the value of bitcoin to drop by more than 50%. Since then prices have partially recovered with a steady rise taking place throughout 2019 to now over $11000 per coin in June 2019.