Bitcoin is a type of cryptocurrency with the symbol '₿' and is a type of money that is completely virtual. It is perhaps the best-known cryptocurrency and is used by around 5 million unique users. Bitcoin was invented in 2008, and was initially released in January 2009. Bitcoin is decentralised so is not controlled by banks or government.
Each Bitcoin is a file stored in a digital wallet, and can be sent (whole or as a part) to other people, or used to pay for goods. Each transaction made with Bitcoin is recorded on a public list, constructed using blockchain technology, which makes the history traceable, meaning it is more secure and stops people spending fake coins they do not own.
Bitcoins are originally created with a computer using a process called mining, where computers have to work to solve complex problems and are rewarded with Bitcoins when solved, but you can buy them with real money or by exchanging them for items.