I decided to look into the world of blockchains, because, regardless of what happens to bitcoin and other cryptocurrencies, blockchains are here to stay. My interest is in blockchains as ledgers, not cryptocurrency. A ledger is just a list of transactions. Blockchains are ledgers that use a decentralized model for verification. The decentralized model is a distributed group of server nodes that verify ledgers and transactions. The verification rests on a set of mathematical models called one-way functions. One-way functions are easy to compute one-way, but computationally impossible to compute the other way.
A really simplified example, with no direct mathematical relation to one-way functions, is the slope of the line which I talk about in my study note on The Linear Hypothesis. Using the formula, if I know the slope, the intercept and X , I can calculate Y. And, conversely, I can calculate X, if I know the slope, the intercept and Y. Well, in the world of one-way functions, it is kind of being able to calculate Y from the given information, but not X. This over simplifies things horribly, but helps me understand the concept. For more information related to the actual math, look up hash functions and elliptic curves.
There are many, many, many blockchain startups in the world. I decided to focus on the Ethereum chain. Ethereum is one of the chains that is moving into smart contracts. Smart contracts are blockchains that include, but are not limited to, currency. The idea is that all kinds of transactions can be verified. This is driving a new approach to the internet, web browsing and apps where everything significant within an app, browsing session, etc. can be verified. Web3 and dapps use Ethereum. I am not going to try to provide links to any of these topics specifically because the links and information change so quickly, but I do find a lot of good information at Wikipedia, HackerNoon and TheMedium. For Ethereum specific information check out ethereum.org and kauri.io.