Bitcoin is a decentralized digital currency that operates without a central bank or administrator. It was created in 2009 by an unknown individual or group using the pseudonym Satoshi Nakamoto. Bitcoin transactions are recorded on a public ledger called the blockchain, which uses cryptography to secure and verify transactions. 

Bitcoin is often referred to as a cryptocurrency because it uses cryptographic techniques to secure transactions and control the creation of new units. It is designed to be scarce, with a maximum of 21 million bitcoins that can ever be created. Bitcoin can be bought and sold on cryptocurrency exchanges or used as a form of payment for goods and services.

Bitcoin has been subject to extreme price volatility over the years, with its value reaching an all-time high of almost $65,000 USD in April 2021, and dropping to less than half of that by September of the same year. The volatility of Bitcoin's price is due in part to its decentralized nature and the lack of regulation in the cryptocurrency market. Despite its volatility, many investors and businesses see Bitcoin as a potential investment opportunity or a means of conducting financial transactions without the need for intermediaries such as banks.