4.1 Routing

• The process of mapping a URL to a handler function or controller in your web application.
• Each framework has its routing system; e.g., URLs.py in Django or app.get() in Express.js.

4.2 ORM (Object-Relational Mapping)

• A way to interact with databases using programming language objects instead of SQL.
• Frameworks like Django (Django ORM) and Rails (ActiveRecord) have built-in ORMs.

4.3 Middleware

• Software that lies between the request and response in a web application.
• In Express, middleware is central to the app's flow.

4.4 Templating Engines

• Tools for embedding data into HTML files dynamically.
• E.g., Jinja in Flask or EJS in Express.js.

4.5 Authentication & Authorization

• Implement secure login systems using frameworks’ built-in libraries.
• Django: Django’s Authentication system.
• Spring: Spring Security.