Starting at the beginning, what is blockchain?
For a nice overview of the space and what happened in 2017, Last Week Tonight with John Oliver did a good episode on cryptocurrencies.
Most people will have heard of Bitcoin by now. Developed in 2008 by the pseudonymous Satoshi Nakamoto. The first implementation of blockchain technology. Allowing people to send value between each other. The most discussed and written about Cryptocurrency.
Ethereum is the next most well known Blockchain. Initially described by Vitalik Buterin in a white paper. Followed by a yellow paper with more technical details (the beige paper attempts to be a more readable version). The main innovation in Ethereum is the support for smart contracts. Allowing the network to run programs, a world computer.
Crypto Zombies is a good tutorial on solidity, the main language used to write smart contracts on Ethereum. Remix is a decent IDE for developing your own contracts, with Truffle a decent framework to help build and test them.