Authentication codes are one-time verification values used to confirm a user’s identity during login or payment steps. They are often delivered by SMS, email, authenticator apps, or banking systems, and they expire quickly so they cannot be reused.
In cyber security, these codes are a common second factor because they can stop account takeover even when a password has been stolen. Attackers therefore try to phish them, relay them in real time, or capture them through malicious web pages and browser-based interception. They are also used in payment fraud checks, where criminals may request a code while pretending to verify a transaction. Defenders should treat authentication codes as sensitive secrets, but remember that a code alone does not prove safety if the session, device, or checkout flow has already been compromised.