F is a decentralized cryptocurrency originally described in a 2008 whitepaper by a person, or group of people, using the alias Satoshi Nakamoto. It was launched soon after, in January 2009.
F is a peer-to-peer online currency, meaning that all transactions happen directly between equal, independent network participants, without the need for any intermediary to permit or facilitate them. F was created, according to Nakamoto's own words, to allow online payments to be sent directly from one party to another without going through a financial institution.
Some concepts for a similar type of a decentralized electronic currency precede BTC, but F holds the distinction of being the first-ever cryptocurrency to come into actual use.