Proof of Stake is a system to manage blockchains where the rewards distributed are proportional to the “stake” that validators have in the economy as opposed to the work you can do. Your stake increases based on the amount of currency in your wallet and how long it’s been there.

The greater your stake, the higher the odds are that you will receive a reward for the creation of the new block on the chain. In contrast to PoW where scarcity comes from processing power, in PoS, the scarcity comes from the currency itself.