What Is Bitcoin (BTC)?

Bitcoin's core idea was set out in the 2008 white paper titled Bitcoin: A Peer-to-Peer Electronic Cash System, and the network began in January 2009 with the creation of the first block (the genesis block). Transactions are recorded on a public blockchain, a copy of which is held by nodes around the world. The network uses the Proof of Work consensus mechanism: miners compete with computing power to produce a new block roughly every 10 minutes.

New bitcoins enter circulation only through mining, as the block reward. The block reward is cut in half every 210,000 blocks, or roughly every four years (halving); for this reason, supply slows progressively and approaches the 21 million cap. Bitcoin's smallest unit is the satoshi, and 1 BTC equals 100 million satoshis. Because of its limited supply, Bitcoin is described by some circles as digital gold.

Bitcoin is used as a means of payment, a store of value and an investment asset; its institutional access has expanded with the approval of spot Bitcoin ETFs in the US in January 2024. Because the mainnet's transaction capacity is limited, second-layer solutions such as the Lightning Network have been developed for fast and small payments. High price volatility, the energy consumption of mining and regulations that vary from country to country are the main topics of debate.