A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and sometimes allows the passage of sound and 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.