A door handle or doorknob is a handle used to open or close a door. Door handles can be found on all types of doors including exterior doors of residential and commercial buildings, internal doors, cupboard doors and vehicle doors. There are many designs of door handle, depending on the appropriate use. A large number of handles, particularly for commercial and residential doors, incorporate latching or locking mechanisms or are manufactured to fit to standardised door locking or latching mechanisms. The most common types of door handle are the lever handle and the doorknob. Door handles can be made out of a plethora of materials. Examples include brass, porcelain, cut glass, wood, and bronze. Door handles have been in existence for at least 5000 years, and its design has evolved since, with more advanced mechanism, types, and designs made. Some door handles are also arm- or foot-operated to reduce transmission of contagious illnesses. Types The most common type of door handle is the Lever latch or Latch door handle on a backplate found in residential houses and commercial and public buildings. Doors fitted with this handle have a latch that keeps the door shut. The door handle has only a lever handle or knob which operates this latch. Pushing the handle down rotates the spindle, operating the tubular latch mechanism inside the door, allowing it to be opened. This type of door handle is used on interior doors that do not require to be locked. The lever latch handle is easy to install and use, and is available in a variety of styles and finishes. The doorknob has a spindle running through it that sits just above a cylinder, to which the spindle is connected. Pushing the lever or turning the knob pulls the cylinder in the direction of the turn. The end of the cylinder is the "latch bolt" (more simply known as the "latch"), which protrudes into a space carved out of the door frame, and which prevents the door from being opened if the knob is not turned. A spring or similar mechanism causes the latch to return to its protruding state whenever the knob is not being turned. The Lever lock door handle on a backplate is another type of door handle which operates similarly to the lever latch door handle. This type of handle on a backplate consists of a lever with a keyhole cut