Power switch
Not
to be confused with a power button, a power switch is like a light switch
that has an on and off position, usually represented by a 1 (on) and a 0 (off).
Every computer today uses a power button for turning on and off a computer.
However, many desktop computer power supplies also have a switch that is found
on the back of the computer, like that shown in the picture to the right. This
power switch turns on and off the power supply and if set to the off position
the power button for the computer will not work.
Also see: Power button, Power definitions, Power supply