Satoshi Nakamoto is the pseudonymous person or group of people who designed and created the original Bitcoin software, currently known as Bitcoin-Qt. His involvement in the original Bitcoin software does not appear to extend past mid-2010.

Identity

There are no records of Nakamoto’s identity or identities prior to the creation of Bitcoin. On his P2P foundation profile, Nakamoto claimed to be an individual male at the age of 37 and of Japanese origin, which was met with great skepticism due to his use of English and his Bitcoin software not being documented nor labeled in Japanese.

British formatting in his written work implies Nakamoto is of British origin. However, he also sometimes used American spelling, which may indicate that he was intentionally trying (but failed) to mask his writing style, or that he is more than one person.

The first release of his original Bitcoin software is speculated to be of a collabrative effort, leading some to claim that Satoshi Nakamoto was a collective pseudonym for a group of people.

Work

Nakamoto has claimed that he has been working on Bitcoin since 2007. In 2008, he published a paper on The Cryptography Mailing List at metzdowd.com describing the Bitcoin digital currency. In 2009, he released the first Bitcoin software that launched the network and the first units of the Bitcoin currency.

Version 0.1 was for Windows only and had no command-line interface. It was compiled using Microsoft Visual Studio. The code was elegant in some ways and inelegant in others. The code does not appear to have been written by either a total amateur or a professional programmer; some people speculate based on this that Satoshi was an academic with a lot of theoretical knowledge but not much programming experience. Version 0.1 was remarkably complete. If Satoshi truly only worked on it alone for two years, he must have spent a massive amount of time on the project.

Nakamoto was active in making modifications to the Bitcoin software and posting technical information on the Bitcoin Forum until his contact with other Bitcoin developers and the community gradually began to fade in mid-2010. Until a few months before he left, almost all modifications to the source code were done by Satoshi — he accepted contributions relatively rarely. Just before he left, he set up Gavin Andresen as his successor by giving him access to the Bitcoin SourceForge project and a copy of the alert key.

Motives

Nakamoto’s work appears to be politically motivated, as quoted:
“Yes, [we will not find a solution to political problems in cryptography,] but we can win a major battle in the arms race and gain a new territory of freedom for several years. Governments are good at cutting off the heads of a centrally controlled networks like Napster, but pure P2P networks like Gnutella and Tor seem to be holding their own.” – Satoshi Nakamoto

“[Bitcoin is] very attractive to the libertarian viewpoint if we can explain it properly. I’m better with code than with words though.” – Satoshi Nakamoto

In the Bitcoin network’s transaction database, the original entry has a note by Nakamoto that reads as:
“The Times 03/Jan/2009 Chancellor on brink of second bailout for banks”

Some claim this quote implies Nakamoto had great concern or contempt for the current central banking system.
Influence

The smallest unit of the Bitcoin currency (1/100,000,000) has been named “satoshi” in collective homage to his founding of Bitcoin.