1. When referring to hardware, a button is a physical switch that controls a function of a device. The picture is an example of the power button found on the front of a computer.
What does the power button do?
- If the computer is off and the power button is pressed the computer turns on.
- If the computer is sleeping and the light is flashing the power button will wake up.
- With more modern computers, if the computer is on and running pressing and letting go of the power button puts the computer into sleep.
- With newer computers if the computer is on and running and you press and hold the power button the computer turns off after holding the button down for a few seconds.
Note: How the power button operates can be changed so the computer may turn off when the power button is pressed.
What is the power button symbol?
The de facto standard for the power button symbol is an almost complete circle with a vertical line going from above the circle down to the center of the circle as shown on this page. The symbol represents a "0" (zero) and a "1" (one), which is the characters used in the computer's binary language and also represents off (0) and on (1).
2. When referring to software, a button is used to perform a certain function. For example, the Windows Start button is used to open the Start menu. See the push-button dictionary definition for further information and an example.