Bitcoin is a decentralized cryptocurrency originally described in a 2008 whitepaper by a person using the alias Satoshi Nakamoto. It was launched soon after, in January 2009. Bitcoin 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. Bitcoin was created, according to Nakamoto 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 Bitcoin holds the distinction of being the first-ever cryptocurrency to come into actual use.

On 3 January 2009, the bitcoin network was created when Nakamoto mined the starting block of the chain, known as the genesis block. Embedded in the coinbase of this block was the text "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks". This note references a headline published by The Times and has been interpreted as both a timestamp and a comment on the instability caused by fractional-reserve banking.

The receiver of the first bitcoin transaction was Hal Finney, who had created the first reusable proof-of-work system -RPoW (based on Nick Szabo's theory of collectibles) in 2004. Finney downloaded the bitcoin software on its release date, and on 12 January 2009 received 10 bitcoins from Nakamoto. Other early cypherpunk supporters were creators of bitcoin predecessors: Wei Dai, creator of b-money, and Nick Szabo, creator of bit gold.

The energy-consumption debate:
Bitcoin's energy consumption, as highlighted by the CCAF, may appear concerning, but it is essential to recognize that energy consumption alone is not inherently harmful. The true concern lies in carbon emissions, which can be mitigated by utilizing renewable energy sources. Encouragingly, the fact that 70% of Bitcoin miners reportedly use renewable energy demonstrates progress toward reducing the industry's carbon footprint. By focusing on increasing the share of renewable energy in the mining process, Bitcoin can contribute to a greener future. It is crucial to consider the broader context of energy usage in various industries and sectors and recognize Bitcoin's potential to incentivize renewable energy innovation while providing financial empowerment and inclusivity to individuals worldwide.