Questions
Background
"Proof of Work is an economic measure to deter denial of service attacks and other service abuses such as spam on a network by requiring some work from the service requester, usually meaning processing time by a computer (Basically what Bitcoin and Ethereum currently use)." The issue is that it requires A LOT of computing power and thus energy, so it's not very efficient or environmentally friendly. (via https://en.wikipedia.org/wiki/Proof-of-work_system)
"Proof of stake (PoS) is a type of algorithm by which a cryptocurrency blockchain network aims to achieve distributed consensus. In PoS-based cryptocurrencies, such as Peercoin[1] invented by Sunny King and Scott Nadal, the creator of the next block is chosen via various combinations of random selection and wealth or age (i.e., the stake). In contrast, the algorithm of proof-of-work-based cryptocurrencies such as bitcoin uses mining; that is, the solving of computationally intensive puzzles to validate transactions and create new blocks." (via https://en.wikipedia.org/wiki/Proof-of-stake)
Personal Notes and Thoughts
Other use
Some websites are even making lists of tokens that use proof of stake, which makes it look a lot like dividends that some stocks give out, or interest that other investment vehicles provide
https://www.poslist.org/ (indeed here they have a column called interest, of July 25th 2018 there are 121 coins listed in this section)
As well as there are more and more articles about the subject:
Reading list