An awning window is a casement window that is hung horizontally, hinged on top, so that it swings outward like an awning. In addition to be used independently, they can be stacked, several in one opening, or combined with fixed glass. They are particularly useful for ventilation.
In the 13th century BC, the earliest windows were unglazed openings in a roof to admit light during the day. Later,[when?] windows were covered with animal hide, cloth, or wood. Shutters that could be opened and closed came next.[when?] Over time, windows were built that both protected the inhabitants from the elements and transmitted light, using multiple small pieces of translucent material, such as flattened pieces of translucent animal horn, thin slices of marble, for example fengite, or pieces of glass, set in frameworks of wood, iron or lead. In the Far East, paper was used to fill windows. The Romans were the first known to use glass for windows, a technology likely first produced in Roman Egypt. Namely, in Alexandria ca. 100 AD cast glass windows, albeit with poor optical properties, began to appear, but these were small thick productions, little more than blown glass jars (cylindrical shapes) flattened out into sheets with circular striation patterns throughout. It would be over a millennium before a window glass became transparent enough to see through clearly, as we think of it now.
Window is first recorded in the early 13th century, and originally referred to an unglazed hole in a roof. Window replaced the Old English eagþyrl, which literally means 'eye-hole,' and 'eagduru' 'eye-door'. Many Germanic languages however adopted the Latin word 'fenestra' to describe a window with glass, such as standard Swedish 'fönster', or German 'Fenster'. The use of window in English is probably because of the Scandinavian influence on the English language by means of loanwords during the Viking Age. In English the word fenester was used as a parallel until the mid-18th century. Fenestration is still used to describe the arrangement of windows within a façade, as well as defenestration, meaning to throw something out of a window.
A sloped window used for daylighting, built into a roof structure. It is one of the few windows that could be used as an exit. Larger roof windows meet building codes for emergency evacuation.