What makes a doorknob turn is its spindle and cylinder, which turn clockwise or anticlockwise when the doorknob is rotated and engage the latch. The spindle carries the action of rotating the doorknob into the cylinder. The movement of the cylinder forces the attached bolt installed in the internal face of the door to slide in or out of the latch of the door's frame. This allows the door to open or shut.
Generally, most doorknobs have a spring or other similar mechanism that causes the latch to automatically return to its protruding state when no one is actively turning it. A door knob with a lock does not turn when the lock is activated. A doorknob is difficult to turn when there is not enough space between the door and the wall to comfortably turn the knob.
Manufacturers produce turning doorknobs from a wide variety of materials, including brass, glass, wood, white porcelain and bronze. In the United States, homeowners tend to prefer door knobs, while European homeowners prefer door levers. For the elderly or very young, there are special doorknobs that do not require a tight grip in order to turn the doorknob and operate the internal latch.