A controller module is a part of the ModelViewController design pattern. It gives you a way to create user friendly urls.

The purpose of this module is to serve files.

A HttpModule can be used to serve urls. The module itself decides if it should serve a url or not. In this way, you can get a very flexible http app since you can let multiple modules serve almost similiar urls.

Used to inform http server that

A reverse proxy are used to act as a bridge between local (protected/hidden) websites and public clients. A typical usage is to allow web servers on non standard ports to still be available to the public clients, or allow web servers on private ips to be available.