Bitcoin Basics

Bitcoin is a digital money system that runs without a bank or company in charge. Thousands of computers keep identical copies of a public ledger and check every transaction against shared rules. The word also names the unit of money, written bitcoin or BTC. What Is Bitcoin? explains the network, the coin and the main risks in plain English.

Bitcoin was created by a person or group using the name Satoshi Nakamoto, whose real identity is unknown. The whitepaper appeared on 31 October 2008 and the first block was created on 3 January 2009. Nakamoto stopped taking part in 2010 and 2011, and nobody has proven a claim to the name. See Who Is Satoshi Nakamoto? and The History of Bitcoin.

Nobody owns the Bitcoin network. Individual coins belong to whoever controls the private keys that can spend them, including individuals, companies, funds and exchanges holding coins for customers. The main software is open source, and rule changes only matter if the people running the network adopt them. What Is Bitcoin? covers ownership and control.

Only 21 million bitcoin can ever exist, a limit written into the software. New coins are released on a schedule that halves roughly every four years, and the last are expected around the year 2140. One bitcoin divides into 100 million satoshis, so owning a fraction is normal. Details are in What Is Bitcoin?, and the schedule is in How Many Bitcoin Are Left to Mine?.

The network started on 3 January 2009 with the genesis block, after the whitepaper of 31 October 2008. Later milestones include the first halving in November 2012, the 2014 collapse of the Mt. Gox exchange, the SegWit upgrade in August 2017 and US spot Bitcoin ETFs in January 2024. The history timeline places each in context.

Bitcoin carries real risks: the price can fall sharply, payments are generally irreversible, lost keys cannot be recovered, no deposit insurance applies and scams target newcomers. Whether it suits you depends on your finances, so learn first and consider a qualified professional. What Is Bitcoin? sets out the risks plainly, and Is Bitcoin Safe? goes deeper.

One bitcoin is 100,000,000 satoshis, so one satoshi is 0.00000001 BTC. A satoshi is the smallest unit recorded on the Bitcoin blockchain, named after Bitcoin's creator. Wallets often show amounts in satoshis, or sats, to avoid long decimals. See How Many Satoshis Are in a Bitcoin?.

It is the nine-page paper "Bitcoin: A Peer-to-Peer Electronic Cash System", published under the name Satoshi Nakamoto on 31 October 2008. It describes how transactions, proof of work and a chain of blocks can let strangers agree on a ledger without a bank. See The Bitcoin Whitepaper Explained.

The genesis block is the first block of the Bitcoin chain, mined by Satoshi Nakamoto on 3 January 2009. It is built into every node's software and its first transaction carries a newspaper headline from that day. See The Bitcoin Genesis Block.

The Bitcoin glossary defines about 45 key terms in plain English, from address and block to UTXO and wallet, and links each one to a fuller guide. New to the subject? The Start Here path puts the core guides in order.

Cryptocurrency is a digital asset recorded on a shared ledger and secured with cryptography, so no bank sits in the middle. Bitcoin, launched in 2009, was the first. Many others exist, with very different designs and risks. See What Is Cryptocurrency?.

Nobody can say for certain. Large amounts sit in wallets run by exchanges and funds for many customers, early holders and the creator's coins are only estimates, and some coins are lost. On-chain addresses are not people. See Who Owns the Most Bitcoin?.