Two Different Questions
Authentication answers who you are by verifying an identity claim, such as a password, passkey, or token. Authorization answers what you may do once identity is known, by checking permissions against a policy.
Why The Distinction Matters
- Confusing them leads to broken access control, where a logged in user reaches data they should not.
- Authentication happens once per session, while authorization is checked on every request to a protected resource.
- A valid token proves identity but never implies permission by itself.
Doing It Well
- Verify identity with strong factors and short lived sessions.
- Enforce authorization on the server side for each action, never trusting the client.
- Apply least privilege so each role gets only the access it needs.
- Log authorization failures to detect probing.
Key idea
Authentication establishes identity and authorization grants access, so enforce both separately and check permissions on every request.