what is a door leaf

A door leaf is the large, swinging panel affixed to the doorframe, which is the most critical part of the door assembly. It is the part of the door that most people think of when they picture a door. A single-leaf door is made of a single panel that sits inside the door frame when closed, and a double-leaf door has two doors that open. Door leaves can be made from a single, solid piece of wood or steel, or they can contain a number of smaller panels, such as rails, stiles, panels, mullions, and glazing. The term "leaf" is used to refer to the door itself, and it is commonly required that only one leaf out of two in a double door have an active leaf (key lock), hence the other is called the inactive leaf