Power down, shut off, switch off, or turn off are all terms used to describe the act of closing all of the applications that are running, and then properly cutting power to a computer along with all other devices connected to it. In the picture to the right, is an example of a power button on the front of a computer. The universal power button symbol is a circle with a vertical line going through the circle as shown in this picture.
How to turn off a computer
With most computers, when you quickly press the power button once, the computer will power off automatically. If you need to turn off a computer because of a problem, you can press and hold the power button for a few seconds to turn it off.
Tip: To learn alternative ways to turn off (shut down) your machine, see our page on how to shut down a computer.
What happens if you turn off a computer when it says not to?
When a computer is performing important updates or other system changes you'll see a message not to turn off the computer while installing updates. If you do turn off the computer or the computer loses power a number of different things can happen.
For example, while Microsoft Windows or another operating system is updating the computer if you turn off the computer during the update. the files being updated may become corrupt causing the computer to have errors or not boot at all. If you turn off a computer during a BIOS or firmware update, the computer or hardware may stop working and may require a hardware replacement.