Greetings! Today, we'll unlock the world of Authorization, with a focus on user roles, Role-Based Access Control (RBAC), and authorization middleware.

To illustrate Authorization simply—it's like a space mission, where only authorized astronauts can enter restricted areas. Now that we understand Authorization, let's implement it in our applications!

Authorization comes into play post-authentication, deciding what actions authenticated users can perform. To break it down, Authentication is a spaceship's identity check, while Authorization is the spacesuit that guides users to access the various compartments of the spaceship.

Imagine a space facility with scientists and engineers, each having defined roles and access levels. Similarly, the Role-Based Access Control (RBAC) system assigns permissions based on roles.

Take an e-commerce system as an example:

• Buyer views products.
• Seller manages their products.
• Admin controls the complete system.

RBAC is essential for managing large system!

In an authorization system, user roles dictate their system access. With MongoDB and Mongoose, we can manage user roles.

1. Creating User Roles: Consider 'User' and 'Admin' roles. To oversee our system, we design a user schema with role as a property.