What is the Proof of Authority (PoA) consensus protocol?

Proof of Authority (PoA) is a consensus mechanism that works by selecting suitable validators based on their reputation. PoA, invented by Ethereum co-founder Gavin Wood in 2017, is a modified version of PoS. Validators do not lock their coins in staking. They use their reputation to get the right to validate blocks. The use of this mechanism does not require high computing power, but the participants have to disclose their identities. Also, the weak point of the Proof of Authority protocol is decentralization, since only selected users can become validators.