Bitcoin is a digital or virtual currency that was created in 2009 by an unknown person or group of people using the name Satoshi Nakamoto. It uses a decentralized system called blockchain to record transactions and manage the issuance of new units. Transactions are verified by network nodes through cryptography and recorded on a public distributed ledger called a blockchain. Bitcoin is unique in that there are a finite number of them: 21 million. Transactions are made directly between users without an intermediary, such as a bank or government. Bitcoin can be used to purchase goods and services online or in-person, and can also be held as an investment. One of the key characteristics of Bitcoin is its decentralization, meaning that there is no central authority controlling it. This decentralized nature makes transactions more secure, as no one person or entity has control over the network. However, Bitcoin has also faced criticism due to its association with criminal activities and its potential for use in illegal transactions. Additionally, the high energy usage required for mining Bitcoin has raised concerns about its environmental impact. Overall, Bitcoin has gained popularity as a decentralized currency and investment opportunity, but it also has its drawbacks and limitations.