[eluser]xwero[/eluser]
Dregond it's just another way to include many files. The included files should be kept to a minimum but they also should contain as less unneeded code as possible. So instead of creating one big file with everything in it, create a few files based on what groups of pages need. And if a single page needs extra code you still can add it separately.
There are some php solutions that join js/css files for you but i think it's better to include static files as much as possible.