Bitcoin

Bitcoin is the first and largest cryptocurrency, launched in January 2009 by the pseudonymous creator Satoshi Nakamoto as a peer-to-peer electronic cash system that operates without banks or governments. It runs on a public blockchain maintained by miners who expend computing power to validate transactions and secure the network, a process called proof of work.

Bitcoin's defining feature is its fixed supply: the protocol caps issuance at 21 million coins, with new coins released on a predictable schedule that halves roughly every four years. This scarcity is why many people treat Bitcoin as a store of value — often called digital gold — rather than everyday spending money. For example, someone in one country can send bitcoin to someone on another continent on a weekend night, and the transfer settles on the blockchain within about an hour without any bank involved.

A common misconception is that Bitcoin is fully anonymous; in reality every transaction is permanently public, and addresses can often be linked to identities through exchanges and analysis. Note the convention: capitalized Bitcoin usually refers to the network and protocol, while lowercase bitcoin (ticker BTC) refers to the currency units themselves. Each bitcoin divides into 100 million smaller units called satoshis.