The basic purpose of a window is to provide light and air. Depending on the activity, at times it may be desirable for sunshine to flood the room; at other times, it may be appropriate to block out strong sunlight. Windows may also open up for a lovely view or exclude an unsightly one and it may be the means of ensuring privacy where privacy is needed. Window treatments can also give a bright look by not concealing the day-light or provide a dark room by total concealment or a subdued light effect by partial concealment. Thus window dressings can do wonders in a number of ways.