Dormer windows aren’t really a special type of window but more a special location to have a window installed. Dormer windows are any windows that installed in a “dormer” which is a bump out feature of the roof. Dormers allow for more room in the floor directly underneath the roof. Often times they are used to make upstairs bedrooms or bonus rooms larger and more usable. When a window is installed in a dormer it helps additional sunlight get into the space and typically provides another way to get out of the house in case of an emergency.