Dormer windows/Windows on Roofs. Dormer windows are windows you can pretty commonly find in townhouses, attics, suburban homes and apartments where there isn'ttalot of space, so they opt for extending out the roof and adding a small space where it streches out and has a window with a roof over it (obviously), making a good spot for desks, beds etc. Windows on roofs are simpler, where they're just a window you can place on the "wall part" of roofs, if that makes sense.