He’s a man of anonymity. And his identity is mostly based upon speculations made by his co-workers, Bitcoin community members and fans. In 2008, he published a paper called “Cryptography Mailing List” where he mentioned about the digital currency that he had been working on, Bitcoin. That paper can be accessed at here.
And in 2009, he released the first version of Bitcoin software. Since Bitcoin is an open source project, meaning its original code is independently available, free to be redistributed and modified. After the initial release he got involved into the development process with others via mailing lists. Despite working almost a year with an open source team, he was good at hiding his personal-self. Yes, he disappeared in 2010 handing over the bitcoin.org (official site) to one of the prominent community members,
At P2P community he claimed to be a 37 years old male from Japan, but many things point into the other direction. Like, the accuracy and non-hesitancy in his written English makes many doubt his claim about him being from Japan. Another thing is that if he is really from Japan, he should have had Bitcoin documentation at least available in Japanese language.
Even his name’s ‘realness’ is in some doubt and many believe Satoshi Nakamoto is a combination of Japanese multinational companies; SAmsung, TOSHIba, NAKAmichi, MOTOrola. He is believed to be a genius. An example of his intelligence is that he resolved the issue of double spending in his concept of Bitcoin, which is the spending of digital currency more than once. Satoshi prevented the risk of double-spending by setting up a public log where every transaction is recorded for users to verify from. Such a mechanism is one-of-kind developed by Satoshi.
He developed the concept behind this digital currency Bitcoin and the software (used to run the system).
At the end of the day, nobody really know who is behind Bitcoin crypto-currency? Though, there have been suggested identities as to whose face might be that of Satoshi Nakamoto.