Authentication
Also called authn.
Authentication checks that a person, application, or service is the identity it claims to be.
Example
You sign in with a password and a security key. That sign-in is authentication. It does not by itself decide whether you may edit a shared document.
Why it matters
A password, a passkey, or a second factor is evidence for that check. Authentication answers “who is this?” AuthorizationAuthorization decides what an identified user or system is allowed to access or do. answers “what may they do?” The short word auth is used for both, so this glossary does not treat it as either one alone.
Common confusion
Authentication is not authorizationAuthorization decides what an identified user or system is allowed to access or do.. Signing in proves an identity. It does not list every action that identity may take.
Sources
Updated September 30, 2026.