Proof of Authority

Proof of authority, or PoA, is a consensus mechanism in which a small, pre-approved set of validators is allowed to produce blocks, and what they put at stake is their known identity or reputation rather than computing power or capital. Because the validator set is fixed and vetted, blocks are produced on a predictable schedule, confirm quickly and cost very little, which is why PoA is common on testnets, enterprise chains and some sidechains. The trade-off is explicit centralisation: whoever controls the validator list can censor transactions, reorder them or halt the chain, and users must trust that operators will not collude. PoA networks are best understood as permissioned systems that borrow blockchain structure.