Window coverings are considered any type of materials used to cover a window to manage sunlight, privacy, additional weatherproofing or for purely decorative purposes.
Superdrug with boarded windows during the 2009 G-20 London summit protests
A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent material, a sash set in a frame in the opening; the sash and frame are also referred to as a window. Many glazed windows may be opened, to allow ventilation, or closed, to exclude inclement weather. Windows may have a latch or similar mechanism to lock the window shut or to hold it open by various amounts.
Alabaster "mullion"-divided decorative windows in Santa Maria La Major church (Morella, Spain)
Alabaster window in the Valencia Cathedral. Note the asymmetrical, slanted left side of the wall-frame, which lets sun rays reach the chancel
Ancient Egyptian sandstone window grill from a palace of Ramesses III, now in the Metropolitan Museum of Art (New York City)
Fragment of a Roman window glass plate dated to 1st to 4th century CE. Note the obvious curvature; this is not a flat pane