What is the difference between authentication and authorization?

Authentication is the process of establishing the identity of a user. Authorization is the process of determining what actions a user can perform after authentication.

For example, when logging into a website:

• Authentication: The system checks whether the entered login and password are correct. If they are, the user is considered authenticated.
• Authorization: After authentication, the system determines which pages and functions the user has access to (for example, whether they can view their profile, edit articles, or administer the site).