Proof of Stake
A consensus mechanism where validators lock up tokens as collateral to earn the right to propose and attest to blocks.
In Proof of Stake (PoS), validators deposit ('stake') a minimum amount of the network's native token — 32 ETH on Ethereum — as collateral. The protocol randomly selects validators to propose blocks and committees of validators to attest to their validity, with selection weighted by stake size.
Validators who act dishonestly (e.g., double-signing) can be 'slashed' — losing part of their staked funds. This economic penalty replaces the energy cost of PoW as the deterrent against manipulation.
PoS uses far less energy than PoW and allows for faster finality. Critics argue it favours existing large token holders and can lead to centralisation over time, though mechanisms like random selection and slashing are designed to mitigate this.