A window is an opening in a wall, door, roof or vehicle that allows the passage of light, 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. You can reduce energy costs by installing energy-efficient windows in your home. They help in filtering air and sunlight, even as they provide passageway to it. Without windows, the rooms would definitely be a lot more dingy. They are also able escape routes in times of fire or accidental locking of doors.