A
push-button (also spelled
pushbutton) or simply
button is a simple
switch mechanism for controlling some aspect of a
machine or a
process. Buttons are typically made out of hard material, usually
plastic or
metal. 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, though even many un-biased buttons (due to their physical nature) require a
spring to return to their un-pushed state. Different people use different terms for the "pushing" of the button, such as
press,
depress,
mash,
hit, and
punch.