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Authentication checks that a claimant controls the authenticators associated with an account; authorization decides whether that authenticated subject may access a resource or perform a particular action. Signing in does not automatically grant every permission: a user may be able to view a project but not delete it.
Authentication and authorization answer different questions
| Question | Authentication | Authorization |
|---|---|---|
| What does it answer? | Who is making a claim in relation to an account or digital identity? | What resource or action may that subject access? |
| What is evaluated? | Whether one or more authenticators associated with the account are valid and controlled by the claimant. | Whether access should be granted, often by evaluating attributes of the subject. |
| What is the result? | An authentication result or event that can establish an authenticated session. | An allow-or-deny decision for a resource or action. |
| Example | A service verifies the account-associated credentials used when a user signs in. | The signed-in user can view a project but is not permitted to delete it. |
A common shorthand is “Who are you?” for authentication and “What can you do?” for authorization. These questions are useful mnemonics, not full technical definitions. NIST describes authentication as determining whether the authenticators used to claim a digital identity are valid, including establishing that the claimant controls authenticators associated with the account. It defines authorization as a decision to grant access, typically automated by evaluating a subject’s attributes. See NIST SP 800-63B-4 and NIST SP 800-63-4.
How the distinction works in an application
Authentication establishes the account context
When someone signs in, the service checks the authenticators presented for the claimed account. Depending on the system, this could involve a password, a security key, or another authenticator. A successful authentication establishes that the claimant has satisfied the service’s sign-in check; it does not mean the person has permission to do everything in the application.
Authorization evaluates a requested action
When the signed-in user tries to open a record, change a setting, or delete a project, the application can evaluate whether that subject is allowed to perform that operation on that resource. The result may differ by action: the user could have permission to view a repository while lacking permission to delete it. Authentication and authorization are related, but a successful sign-in does not imply that every later access request must be allowed.
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OAuth 2.0 and OpenID Connect are not interchangeable
OAuth 2.0 is for delegated access
RFC 6749 defines OAuth 2.0 as an authorization framework that lets an application obtain limited access to a protected HTTP service, including access delegated on a resource owner’s behalf. An OAuth access token is used in that access framework; by itself, it is not standardized proof of a user’s identity.
OpenID Connect adds an identity layer
OpenID Connect adds an identity layer to OAuth-based flows. In NIST’s federation guidance, an OpenID Connect ID Token is a signed assertion carrying information about the subscriber and authentication event. An OAuth access token serves a different purpose: it protects access to an API, such as the UserInfo endpoint. The tokens should not be treated as interchangeable simply because they may appear in the same flow. See NIST SP 800-63C-4.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Which standards apply, and what their dates mean
NIST SP 800-63-4, Digital Identity Guidelines, was published in July 2025 and supersedes SP 800-63-3. Its scope covers identity proofing, authentication, and federation for people interacting with government information systems over networks; its requirements do not automatically govern every private application. The definitions are useful beyond that scope, but a product’s actual policies depend on its design and applicable obligations.
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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallRFC 6749, The OAuth 2.0 Authorization Framework, is an IETF Standards Track document dated October 2012. The RFC Editor notes that it has subsequent updates, so implementation decisions should account for the current RFC series rather than treating the original document as a complete, current security profile.
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