How to implement centralized processing of all requests to the site?

Question

PHP

Give examples of a beautiful implementation of the structure of an application (in this case, a site), in which requests for all pages are processed by one main controller.
The advantages and disadvantages of this approach are also interesting.

Answer 1

Do you mean an application with a single entry point? Or just one controller? If the latter, then such an architecture has no advantages. If the former, then one entry point - less duplication of code during initialization, it is easier to implement routing to controllers.

Answer 2

For example, on the basis of CodeIgniter, you can make one controller and register all pages in routes.
Are the site pages the same?