Bitcoin
Definition: A decentralized digital currency that runs without banks, governments, or middlemen. Bitcoin exists only online and is powered by a global network of computers verifying and recording transactions on a public ledger called the blockchain. Created in 2009 by an anonymous figure known as Satoshi Nakamoto, Bitcoin lets anyone send money directly to anyone else, anywhere in the world, without needing permission. Its supply is capped at 21 million coins, making it scarce by design and often compared to digital gold.