Bitcoin
Last reviewed November 1, 2026
The Bitcoin network has been running without a break since January 2009. It was the first cryptocurrency and is still the largest by market value.
On 31 October 2008, someone using the name Satoshi Nakamoto published a nine-page paper titled "Bitcoin: A Peer-to-Peer Electronic Cash System". The first block followed on 3 January 2009. Who Satoshi was has never been established.
Bitcoin was designed as electronic cash with no middleman. Today many people treat it more as a store of value, a sort of digital gold. Both views rest on the same technical properties.
Why supply stops at 21 million
New bitcoin only enters circulation as a reward to miners, and that reward halves every 210,000 blocks, roughly every four years. Total supply therefore creeps towards 21 million BTC without ever reaching past it. At the current pace the last fraction of a bitcoin will be mined around 2140.
The halving
The most recent halving, in April 2024, cut the block reward from 6.25 to 3.125 BTC. The next is expected in 2028. Whether halvings move the price is debated: the dates are known years ahead, and markets tend to price in what's predictable.
Mining
Miners bundle transactions into a block and keep trying numbers until the block's hash meets a target. The first to find one adds the block and collects the reward plus fees. Every 2,016 blocks the network adjusts the difficulty so that blocks keep arriving about ten minutes apart.
At household electricity prices, home mining rarely pays. See staking and mining.
The Lightning Network
The Bitcoin blockchain handles only a few transactions per second. Lightning sits on top: payments travel through channels between users and only touch the blockchain when a channel opens or closes. Small payments settle in seconds for a fraction of a cent.
Spot bitcoin ETFs
US regulators approved spot bitcoin ETFs in January 2024. Buying an ETF gives you fund shares, not bitcoin. It is convenient inside a brokerage or retirement account, but you pay an annual fee and you cannot move the coins to your own wallet.