HTTP 402 is a reserved web status code meaning Payment Required. In practice, it is rarely used on the public web, but some payment-aware systems use it as a natural way to signal that a request must be paid for before access is granted. This makes the status code part of the access-control flow, not just a billing message.
In cyber security, HTTP 402 matters because it ties money, authorization, and service access together. If a server trusts a client too much, attackers may try to replay payment messages, forge completion signals, or abuse weak verification to get content without paying. Defenses include server-side validation of payment proofs, idempotency checks to stop duplicate charges, audit logs, and strict limits on what a paid request can unlock. Used well, HTTP 402 can support secure microtransactions; used badly, it can become a new bypass point.