What are door handles?

A door handle is a set of handles on each side of your door. These are connected through the door using a spindle and held using mounting bolts or brackets. The spindle turns the latch using a protruding handle and engages the door frame. It prevents the door from opening.
So, when the door handle moves, it rotates the spindle, and the same retracts the latch. As a result, the root opens.