Proof of Authority (PoA)
A consensus model where a few known, approved validators secure the chain — efficient, but trusted rather than trustless.
Proof of Authority relies on a small set of explicitly approved, identity-known validators to produce blocks, rather than open competition via work or stake. Because validators are vetted and accountable, PoA chains are fast, cheap, and efficient — but they’re permissioned and centralized by design.
PoA suits contexts where some trust is acceptable in exchange for performance: private enterprise chains, testnets, and certain sidechains (BNB Chain uses a PoA-like model). It’s essentially the opposite of crypto’s trustless ideal — you’re trusting the named validators not to collude or censor. That makes it pragmatic for specific uses and inappropriate for applications where censorship-resistance is the point. A clear example that “blockchain” and “decentralized” are not synonyms.