What is authentication and authorization, and how do they differ?

Authentication — the process of verifying a user's identity, i.e., confirming that the user is who they claim to be. For example, entering a login and password.

Authorization — the process of determining a user's rights and access to resources after successful authentication. That is, what the user is allowed to do in the system.

The difference is that authentication answers the question "Who are you?", while authorization answers "What are you permitted to do?".

Example: a user enters a login and password (authentication), after which the system checks whether they have rights to view a specific page or perform an operation (authorization).