Satoschi Nakamoto is the mysterious person, organisation, team or agencie behind bitcoin.
His first appearance
Satoshi startet developing the bitcoin code as early as to 2007.
In August 2008 he registered the domain Bitcoin.org.
Them in October 2008 he made his first public appearance when he published the Bitcoin whitepaper.
The Whitepaper: https://bitcoin.org/bitcoin.pdf
The first Bitcoin
In January 2009 the time had come: Satoshi released the first bitcoin version and started the network with the mining of the so called "Genesis" Block.
He continued to be involved in the development of bitcoin until the middle of 2010.
Identity
The most astonishing thing about him: Nobody knows if he is even a person!
Until now his identity is not known for shure.
Of course there are perons who claim to be Satoshi or were suspected to be Satoschi, but
there are not any real evidence that one of them is really Satoschi.
It just remains a mystery!
Information
If u want to know more about Satosci, I would recommend you the Satoshi Nakamoto Institut:
https://nakamotoinstitute.org
or this great article: https://www.coindesk.com/nobody-understands-bitcoin-thats-ok
Have an nice day!