Bitcoin is an open-source cryptocurrency created by the pseudonymous Satoshi Nakamoto. It is a decentralized digital currency that uses peer-to-peer technology to operate without a central authority. Transactions are verified through a proof-of-work system and recorded in a public distributed ledger called a blockchain. While bitcoin offers advantages like instant transactions and anonymity, it also faces challenges like volatility, scalability issues, and the risk of losing coins if private keys are lost. Overall, bitcoin remains a controversial new currency that some see as the future while others see risks in its use and acceptance.