Authentication
Authentication is the process of establishing that a claimant controls one or more authenticators bound to an account, such as a password or security key.
What a successful sign-in tells you
A sign-in service checks whether you can use an authenticator attached to the account. That might mean supplying its password or proving control of a security key. This is authentication, often shortened to AuthN.
It is a narrower claim than “we know who this person is.” Someone using a stolen password may pass a password check. Identity proofing addresses the real-world identity behind an account; authentication checks access to its authenticators.
Start troubleshooting at the right place
A support analyst may sign in to an admin portal successfully but be unable to change a user’s authentication method. The sign-in worked. The analyst still needs permission for that operation, which is an authorization decision.
Before resetting a password to fix an access problem, establish whether the sign-in failed or the application refused an action after sign-in. Changing the password will not grant a missing role.