Bitcoin was introduced in a 2008 whitepaper titled "Bitcoin: A Peer-to-Peer Electronic Cash System". It solved the long-standing double-spend problem without needing a trusted central authority, using a proof-of-work blockchain secured by a global network of miners. Its fixed supply of 21 million coins makes it inherently scarce — a property often compared to digital gold. Bitcoin can be sent anywhere in the world, at any time, without permission from banks or governments, making it a foundational technology for open, borderless finance.