Bitcoin

Bitcoin is the world's first decentralised digital currency, launched on 3 January 2009 by the pseudonymous Satoshi Nakamoto (whose real identity remains unknown to this day). The Bitcoin whitepaper, titled 'Bitcoin: A Peer-to-Peer Electronic Cash System', was published in October 2008 in the aftermath of the global financial crisis; the genesis block famously encodes the headline 'The Times 03/Jan/2009 Chancellor on brink of second bailout for banks', signalling the project's response to central-bank policy. Bitcoin introduced the concept of a peer-to-peer electronic cash system that operates without any central authority, bank, or government. Transactions are verified by network nodes through cryptography and recorded on a public distributed ledger called a blockchain.

Bitcoin's total supply is hard-capped at 21 million coins — an economic property that cannot be changed without breaking backwards compatibility with the network's rules — making it a scarce, deflationary asset that is often compared to digital gold. New bitcoins are created through a process called mining, where specialised computers (ASICs) solve computational puzzles to validate transactions and secure the network in exchange for the block subsidy. The rate of new bitcoin creation is halved approximately every four years in an event known as the 'halving.' The most recent halving, in April 2024, reduced the block subsidy from 6.25 BTC to 3.125 BTC per block. All Bitcoins in existence are expected to be issued by approximately the year 2140, after which miners will be compensated solely by transaction fees.

Over the years, Bitcoin has evolved from a niche experiment among cryptographers to a globally recognised store of value and medium of exchange. It is accepted by thousands of merchants, held on the balance sheets of publicly traded companies (MicroStrategy, Tesla, Block), and recognised as legal tender in El Salvador (since 2021). In January 2024 the U.S. SEC approved spot Bitcoin ETFs from BlackRock, Fidelity, Ark, and others, opening Bitcoin exposure to traditional investment accounts and pulling tens of billions of dollars of institutional flows into the asset. Bitcoin's market capitalisation consistently places it among the most valuable assets in the world.

Bitcoin has evolved technically through soft-fork upgrades. SegWit (2017) fixed transaction malleability and enabled the Lightning Network — a Layer 2 payment channel network that supports near-instant, low-fee Bitcoin payments. Taproot (2021) added Schnorr signatures, script-path spending via MAST, and improved privacy for advanced spending conditions. Ordinals (2023) opened up an ecosystem of on-chain data inscriptions and BRC-20 tokens on Bitcoin, followed by Runes (2024) and the ongoing BitVM and covenant proposals aimed at bringing more expressive functionality to Bitcoin without changing its foundational security model.