Your computer is obviously an electronic device, and its many components of course require power. Like the case, most people don't give much thought to the power supplied to the system. The power supply in your PC can be compared to the officials at a baseball game: if they are doing their jobs properly nobody really notices them, but if they aren't, everybody knows it and isn't very happy about it.

There are two aspects to power in the PC:

External Power: External power refers to the power that is delivered to the back of the system case. There are several considerations regarding this power and how it is supplied that will determine if your internal power supply is going to work the way it should.

Power Supply: The power supply is the small box that sits inside your case and takes the external power you supply to the computer. Its main job is to transform this power into a form the rest of the computer can use.