Proof of Stake (PoS) is a consensus mechanism where validators are selected to create new blocks based on the amount of cryptocurrency they have staked as collateral.
How PoS works: Validators lock up tokens as stake, selected to validate blocks based on stake size (often with randomization), earn rewards for honest validation, and stake is slashed for malicious behavior.
PoS advantages: Much lower energy consumption than PoW, lower barrier to entry (no expensive hardware), and supports faster transaction finality.
PoS variations: Pure PoS (Algorand), Nominated PoS (Polkadot), Liquid PoS (Tezos), and Delegated PoS (EOS, Tron).