Authentication vs Authorization Explained

Authentication and authorization are related but fundamentally different concepts in application security. Authentication = Who are you? Authentication verifies the identity of a user or application. Examples include: Username and password Multi-factor authentication Certificates OAuth/OIDC Microsoft Entra ID Authorization = What are you allowed to do? After the identity has been established, authorization determines which resources and operations that identity can access. For example: A user may successfully authenticate into an application but only have permission to: View customer records Create support cases Update their own profile They may not have permission to delete customer data or manage system configuration. A typical flow is: User → Authentication → Identity Established → Authorization → Resource Access In enterprise applications, both are critical. Strong authentication with poor authorization can still result in serious security problems if users receive excessive permissions. Modern applications should therefore implement principles such as: Least privilege Role-based access control Strong authentication Secure token handling Proper session management Regular access reviews Separation of duties The simplest way to remember the difference is: Authentication determines "Who are you?" while authorization determines "What are you allowed to do?