authentication
[C/U] Both
This term carries a heavy technical weight in modern digital security, evoking the image of a digital gatekeeper verifying a secret key or a biometric signature. It differs from authorization, which determines what a user is allowed to do; authentication is strictly about confirming identity.
Countable when referring to a specific instance or method of verification (e.g., a biometric authentication). Uncountable when referring to the general security process or the act of proving authenticity.