A verifier is an independent checker that tests whether a result is valid, consistent, or logically sound. In AI and security workflows, the verifier does not have to generate the answer itself; its job is to inspect a candidate output and reject anything that breaks rules, constraints, or expected structure.
Verifiers matter because generated output can look plausible while still being wrong or unsafe. In cyber security, they can validate proofs, policy decisions, detection logic, or code before it is trusted or deployed. Attackers may try to exploit systems that skip verification, while defenders use verifiers to catch malformed inputs, incorrect model output, and logic errors. In practice, a strong verifier turns AI from a free-form generator into part of a controlled validation pipeline.