Authentication is the process of verifying who the user is.
- In ASP.NET MVC, authentication means checking if the user is logged in or not.
- It ensures that the user is genuine and valid.
- Common methods: Forms Authentication, Windows Authentication, OAuth, etc.
Example: When a user logs in using a username and password, the application verifies those credentials — this is authentication.
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What is Authorization?
Authorization is the process of checking what the authenticated user is allowed to do.
- It decides what resources or actions the user can access.
- In MVC, we use [Authorize] attribute to restrict access to certain actions or controllers.
Example: After login, if only Admins can access the "Admin Panel", that check is done using authorization.
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Simple Difference:
| Feature | Authentication | Authorization
-------------------------- --|--------------------------------- --|---------------------------------
Meaning | Who are you? | What can you do?
Comes First | Yes | After authentication
Purpose |Verify identity | Grant access
ASP.NET MVC Tool | FormsAuth, Identity, OAuth | [Authorize], Roles, Policies
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Bonus Tip for Interview:
> “Authentication checks identity, Authorization checks permissions. You must authenticate first, then authorize.”