10 years ago from today, an anonymous guy called Satoshi Nakamoto created the original Bitcoin Whitepaper - An 8 page introduction and technical explanation of the first blockchain to exist.
If you haven't read it, now is the time!
That's It! Pretty easy stuff eh?
In case that's too fuzzy you can find the original pdf from bitcoin.org here: https://bitcoin.org/bitcoin.pdf
Yes, that is some pretty complex stuff but it lays down the framework that all blockchains have evolved from!