Bitcoin was invented by an unknown person Satoshi Nakamoto in the year 2008. But there is no valid proof for this because the person behind bitcoin has never given an interview. It was released as open-source software in 2009. It was the first successful virtual currency designed with faith and equivalent to authorized currency of centralized government. It is a digital currency that uses rules of cryptography for regulation and generation of units of currency. It is commonly called decentralized digital currency.