When it comes to mining, I'm more or less aware of how Bitcoin's simple SHA256 mining works, how Litecoin & similar attempted (and failed) to introduce ASIC-resistance with Scrypt, and how Ethereum seemingly managed to do it with ETHASH and its huge DAG. I've heard, though, that new coins aren't really using ETHASH variants, and there are many interesting alternatives floating around. To organize those in a single place, can anyone:
Define the main high-level characteristics of existing mining algorithms?
Explain how they compare with Ethereum's mining algorithm?