Until now, we have seen simple applications with only one single entry point to access. However, a single entry point isn't enough for more general applications. In advanced web applications, in fact, we have not just a single entry point but often three: frontend, backend, and a common area used as shared zone for every entry point.
The frontend entry point is a public access that is available to all users without restrictions.
On the other hand, the backend entry point is a restricted access available only for authenticated users that have administration roles for managing content in the web application.
Finally, the common entry point is used to share data between entry points.
Think about a reservation system, where frontend is the website displaying room availability and prices, while backend is the administration area, where operators can manage rooms.
In the same way, another example of frontend and backend could be a newspaper website...