Proof-of-Stake (PoS) is a consensus mechanism that verifies blocks on the blockchain using the computers of validators (node operators). Validators must surrender their tokens as collateral to the network as staked tokens.

The main purpose of Proof-of-Stake is to drastically reduce network congestion, improve the speed and eliminate environmental issues that cloud Proof-of-Work. The majority of major blockchains now use PoS and also develop it in their own ways, eg. Sharding.