Authentication and Authorization Best Practices (OAuth2, JWT)

In the realm of modern Python applications, particularly APIs and web services, establishing trust and controlling access are paramount concerns. Developers must implement robust mechanisms to verify the identity of users or clients (authentication) and then determine what actions those verified entities are permitted to perform (authorization). Failing to address these aspects effectively leaves applications vulnerable to unauthorized access and data breaches.

Authentication answers the fundamental question: 'Who are you?' It's the process of verifying a user's claimed identity, typically involving credentials like usernames and passwords, or perhaps more modern methods like multi-factor authentication or biometric checks. Authorization, conversely, tackles 'What are you allowed to do?' Once identity is confirmed, authorization checks decide if the authenticated user or service has the necessary permissions to access a specific resource or execute a particular function.