$BTC Bitcoin (BTC) is the original decentralized digital currency, created in 2009 by an anonymous entity named Satoshi Nakamoto. It allows peer-to-peer transactions without banks or central authorities. All transactions are recorded on a public, immutable ledger called the blockchain, secured by cryptography. Bitcoin's supply is limited to 21 million, often leading to it being called "digital gold." It's traded globally and its value fluctuates based on demand and adoption.