In the past, it was not recommended to use the power button to turn off your PC as Windows would not go through its shutdown process and save all information; you ran the risk of losing information in files you may have just worked on.
However, with newer motherboards (the main circuit board in the PC) in the 2000s, the power switch when pushed sends a signal to Windows to do the shutdown process.
However, you should normally just click the power button and not hold it in, as a click starts the shutdown process and holding the power button down for about 10 seconds arbitrarily shuts the power down. If your PC will not shut down normally, then holding the button for 10 seconds is a way to arbitrarily turn off the electricity to it.
With Windows 8, there is no longer a “Start” button with the option to shutdown and using the power button is a suggested method.
Send your questions to Dwight Watt at firstname.lastname@example.org. He teaches at a technical college in northwest Georgia and does consulting work for businesses and individuals. His website is dwightwatt.com.