A door is a panel that makes an opening in a building, room or vehicle. Doors are usually made of a hard, impermeable and hard-to-break substance but sometimes consisting of a hard frame into which windows or screens have been fitted. Doors are often attached by hinges to a frame. The main purpose of a door is to control physical access. Doors are significant in preventing the spread of fire and as a barrier to noise. They are equipped with locking mechanisms to allow entrance to certain people and keep out others. Doors used to manage the physical atmosphere inside a room so that heating or cooling of interiors may become more effective. It also plays a significant role in preventing the spread of fire or smoke.