Push-button :- Push-button (also spelled pushbutton) or simply button is a simple switch mechanism to control some aspect of a machine or a process. Buttons are typically made out of hard material, usually plastic or metal. Push-button is a switch in the shape of a small button or knob. When it is pushed it completes an electrical circuit that controls something. For example, a doorbell rings when a person pushes a button, or numbers are displayed on a calculator or even when you are playing a machine game at an arcade.
The surface is usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed or pushed. Buttons are most often biased switches, although many un-biased buttons (due to their physical nature) still require a spring to return to their un-pushed state.