Bitcoin was created by a pseudonym, Satoshi Nakamoto and was launched in January 2009 as an alternative to the centralised monetary system or the fiat currencies.
It is a digital currency, a peer-to-peer electronic cash system that helps you to transfer value to someone securely over the internet and at a fraction of cost compared to banks.
In simple words, Bitcoin is an electronic file having a value that is stored in the digital wallet. You can send Bitcoin (in full or part) to other digital wallets belonging to other people.
It functions independent of any centralised monetary authority and is based on blockchain technology. Blockchain technology is the system of recording digital information that eliminates chances of fraud, data manipulation or deletion.