When you a make a request to a web application, that request is sent to the back end of the application. The back end then retrieves all of the necessary information from the database that in needs to fulfill your request. That information is then passed to the front end where it’s used to render the requested page.
Let’s say you’re building a web application based around recipes — recipe objects.
Let’s say you make a request to view a page that displays all of those recipe objects. Remember, when you make that request — by typing a URL into your browser — the request is handled by the back end.
The back end then communicates with the database to retrieve all of the recipe objects.
It then passes those objects off to the front end, where they’re rendered and displayed to you back in your browser. Request fulfilled.