Bitcoin ($BTC) is a type of digital money that exists only online. It was created in 2009 by a person or group called Satoshi Nakamoto. Unlike traditional money, Bitcoin is not controlled by a government or bank. Instead, it works on a technology called blockchain, which keeps track of all transactions in a secure and public way. Bitcoin can be sent directly between people anywhere in the world, without the need for a middleman. There is a limit to how many Bitcoins can ever be made—21 million—making it a rare and valuable asset for many users.