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Authentication is the process of establishing the identity of a person or service that wants to access a resource. It involves the act of challenging a party for legitimate credentials and provides the basis for creating a security principal for identity and access control. It establishes whether the user is who they say they are.
Authentication establishes the user’s identity, but authorization is the process of establishing what level of access an authenticated person or service has. It specifies what data they’re allowed to access and what they can do with it.
Here’s a diagram that shows the relationship between authentication and authorization:
The identification card represents credentials that the user has to prove their identity (you’ll learn more about the types of credentials later in this module.) Once authenticated, authorization defines what kinds of applications, resources, and data that user can access.