What Proof of Authority proves
Proof of Authority proves that an approved validator signed a block. The validator's identity and permission to participate matter more than mining power or staked capital.
This makes PoA attractive for private networks, enterprise chains, and consortium ledgers where participants already know each other and want faster finality without public mining or a fully open validator set.
How PoA works
In Besu, QBFT and IBFT 2.0 are proof-of-authority protocols. A validator pool creates blocks, and existing validators can vote to add or remove members. These protocols can provide immediate finality when enough validators participate correctly.
The system is efficient because it does not need thousands of unknown parties to compete for every block. It also means the network's decentralization is bounded by the validator admission process.
Chains that use Proof of Authority
Proof of Authority is common in private Ethereum-style networks, Besu consortium networks, testnets, enterprise ledgers, and application-specific networks where validator membership is intentionally limited.
Public chains have also used authority-style models, but readers should inspect the validator list, governance process, legal accountability, and whether users can independently exit or verify the network's state.
Tradeoffs readers should know
PoA can be fast, inexpensive, and operationally simple. It can also be much less trustless than PoW or open PoS because validator membership is permissioned.
A good PoA review asks who appoints validators, how many are needed for liveness and finality, whether validators can be removed, what happens during disputes, and how users audit state if governance fails.