Functions of doors

Doors open and doors close. Sometimes they open to the interior of a building but often fire codes require exterior doors to open swinging outward to the outside. Door can also roll up and roll down but these are most often found at businesses where goods from trucks are moved in and out of the building.

Most all home doors use three or more hinges to keep one side of the door secured to the door frame allowing the open side of the door to move from the door frame. Frequently the free moving side of the door contains a latch to keep the door closed at the door frame. This latch can be moved by turning a doorknob. Some latches are equipped with a locking mechanism. Whenever you turn the doorknob, most often, you will find that the hinged side of the door squeaks a bit to announce your exit or entry.