Authentication vs Authorization
Authentication and authorization sound alike and often get confused, but they answer two different questions and always happen in a fixed order. Both live inside the AAA framework.
Last updated August 2026
| Aspect | Authentication | Authorization |
|---|---|---|
| Question it answers | Who are you? | What are you allowed to do? |
| Purpose | Verifies identity | Grants or denies access to resources |
| When it happens | First, at sign-in | After authentication succeeds |
| Based on | Credentials and factors (password, token, biometric) | Permissions, roles, and policies |
| Example | Logging in with a password plus an authenticator code | Being allowed to read a file but not delete it |
| Place in AAA | The first A | The second A, then Accounting |
The bottom line
Authentication proves who you are; authorization decides what you can do once you are in. Authentication always comes first. Both sit inside the AAA model: Authentication, Authorization, and Accounting.
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FAQ
Which comes first, authentication or authorization?
Authentication. The system must confirm who you are before it can decide what you are allowed to do.Where does accounting fit in?
Accounting is the third A in AAA. After you authenticate and are authorized, accounting records what you did through logging, auditing, and session data.
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Written to the CompTIA Security+ SY0-701 objectives. CompTIA and Security+ are trademarks of CompTIA, used here for identification only.