Crypto mining was supposed to be decentralized: a way for everyone to participate in a community, earn money & improve validity, authenticity, and reliability of transactions as a spinoff benefit. Unfortunately, server farms, hardware mods and just the cost of energy have all but pushed the Average Joe out of the mining space, threatening to centralize crypto mining resources and compromise the integrity of the system derived by community. But Ethereum's Casper looks like a way to solve some of those challenges.
What is Proof of stake?
Proof of stake will make the entire mining process virtual and replace miners with validators.
This is how the process will work:
The validators will have to lock up some of their coins as stake.
After that, they will start validating the blocks. Meaning, when they discover a block which they think can be added to the chain, they will validate it by placing a bet on it.
If the block gets appended, then the validators will get a reward proportionate to their bets.
Casper is the POS protocol that Ethereum has chosen to go with. While there has been an entire team busy creating it, Vlad Zamfir is often credited as being the “Face of Casper.”

So how is Casper different from other Proof of Stake protocols?
Casper has implemented a process by which they can punish all malicious elements. This is how POS under Casper would work:
The validators stake a portion of their Ethers as stake.
After that, they will start validating the blocks. Meaning, when they discover a block which they think can be added to the chain, they will validate it by placing a bet on it.
If the block gets appended, then the validators will get a reward proportionate to their bets.
However, if a validator acts in a malicious manner and tries to do a “nothing at stake”, they will immediately be reprimanded, and all of their stake is going to get slashed.
https://blockgeeks.com/guides/ethereum-casper/