In Proof of Authority (PoA), instead of offering up a resource like computing power (PoW) or a financial stake (PoS), Proof of Authority (PoA) relies on validators staking their reputation. Compared to PoW and PoS networks which allow anyone to join without revealing their identity, PoA validators must be known and trusted, thus better suited for private blockchains. As a limitation, PoA validators tend to be a small group and more heavily centralized.