Bitcoin is a decentralized digital currency that uses cryptography for security and is not controlled by any government or financial institution. It was the first cryptocurrency to be created and has inspired the development of many others. Transactions with bitcoin are recorded on a public ledger called the blockchain. Bitcoin can be used to purchase goods and services online and in some cases, offline. Its value is determined by supply and demand in the market, with its price fluctuating over time. Some people see bitcoin as an investment opportunity, while others use it as a means of exchange for goods and services.