****WTF is the blockchain?, by Mohit Mamoria
Understanding the problem it solves before defining it
****Ever wonder how bitcoin (and other cryptocurrencies) actually work?, by 3Blue1Brown
****How the Bitcoin protocol actually works, by Michael Nielsen
****Ethereum in 25 minutes, by Vitalik Buterin
****How does Ethereum work, anyway?, by Preethi Kasireddy
****Decrypting crypto, from bitcoin and blockchain to ICOs, by Alex Rampell
****An Introduction to Crypto, by Linda Xie
****Cryptographic hash function, by Khan Academy
****Basic Primer on Blockchain, by Chris Berg, Sinclair Davidson, and Jason Potts
****Basic terminology for Ethereum, by Matt Condon
****Beginner's Guide Series on Cryptoassets, by Linda Xie