Bitcoin () is a cryptocurrency, a form of electronic cash. It is the world's first decentralized digital currency, and it was designed to work without a central bank or single administrator. Bitcoins are sent from user to user on the peer-to-peer bitcoin network directly, without the need for intermediaries. Transactions are verified by network nodes through cryptography and recorded in a public distributed ledger called a blockchain. Bitcoin was invented by an unknown person or group of people using 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. Research produced by the University of Cambridge estimates that in 2017, there were 2.9 to 5.8 million unique users using a cryptocurrency wallet, most of them using bitcoin.
A bitcoin faucet is a reward system, in the form of a website or app, that dispenses rewards in the form of a satoshi, which is a hundredth of a millionth BTC, for visitors to claim in exchange for completing a captcha or task as described by the website. There are also faucets that dispense alternative cryptocurrencies. The first bitcoin faucet was called The Bitcoin Faucet and was developed by Gavin Andresen in 2010. It originally gave out 5 bitcoins per person.