Skylights are basically windows that are not vertical, but usually closer to horizontal as they sit on top of the roof. Most are fixed but some open a bit for summer ventilation. There also exist roof windows which are basically skylights that open wide and are much more common in Europe where ...
I have reproduced below an article from the construction professional publication Solplan Review November 2008 because it was such a good article on this complicated subject. In 2023, Solplan Review is no longer in publication. For an animation on what is a rainscreen, follow this link.
But...
