Bitcoin is the first cryptocurrency and the largest by market value. It runs on a decentralized network of computers that records every transaction on a public ledger, the blockchain, with no bank or company in the middle. The pseudonymous Satoshi Nakamoto published the design in a 2008 paper, "Bitcoin: A Peer-to-Peer Electronic Cash System," and mined the first block on January 3, 2009. Nakamoto's identity has never been confirmed.
How it works
Bitcoin secures itself through proof of work. Miners run specialized hardware that competes to solve a math puzzle; the winner adds the next block of transactions and collects newly issued coins plus fees. The puzzle is hard to solve and trivial to verify, which is what makes rewriting the chain expensive enough to deter it. Difficulty adjusts roughly every two weeks to keep new blocks landing about every ten minutes. Thousands of independent nodes worldwide keep their own copy of the ledger and reject any block that breaks the rules, so no single party controls the record.
The supply is capped at 21 million BTC, written into the protocol. New issuance falls by half every 210,000 blocks, about every four years, an event called the halving. The fourth halving, in April 2024, cut the block reward from 6.25 to 3.125 BTC. The last coins are expected to be mined around 2140, after which miners earn from transaction fees alone. That fixed schedule is the core of the case for Bitcoin as scarce, gold-like money.
What it's used for
Most holders treat Bitcoin as a long-term store of value, a bet on scarcity rather than a day-to-day currency. It also settles cross-border payments and serves as the base asset for much of the crypto market. Since January 2024, U.S. spot Bitcoin ETFs have let investors hold exposure through a brokerage account, which pulled large flows from traditional finance. People who want to hold the coin directly use a crypto wallet and typically buy on an exchange such as Coinbase.
The markets read
Bitcoin is volatile. It has run through several drawdowns of more than 50% from peak and recovered each time, but past recoveries do not guarantee the next one. It is not a stablecoin: nothing pegs its price, and it can move sharply on ETF flows, a stronger dollar, or a risk-off turn in equities. The asset trades around the clock, including weekends, so it can reprice while traditional markets are shut. Proof of work does not pay holders a yield, unlike staking on networks that use it; the only way Bitcoin pays you back is price. New buyers usually meet it through an exchange, and our buying crypto guides walk that first step. What the fixed supply tells you is the issuance schedule. What it does not tell you is the price, which the market sets day to day.