A door leaf is a single, independently moving panel of a door. The single-leaf door is the most common variety of door. It features a single panel that fills an entire doorway space.
Double-leaf doors, also known as French doors, have two panels that each open outward. Doors are used to block or allow access to spaces. They usually have an interior and exterior side and consist of a panel with a hinge or swinging mechanism. Doors are also used to control air flow and temperature within a space, and they are sometimes used to screen areas for visual enhancement. The earliest records of doors are in paintings in tombs of ancient Egypt.