Power

The infrastructure that makes a city includes not only highways and mass transportation but also utilities, which supply businesses and homes with what they need in the modern world: water, sewers, gas, and electricity.

Computers, too, need utility supplies to keep them going. As mere electronic beasts, however, they need neither water nor gas, and whatever sewage they create usually gets stored on their hard disks rather than carted away. Electricity is the sole necessity of the computer.

Not just any electricity will do. Computers have a definite and strict requirement for the power they use, which fortunately for us corresponds to ordinary utility power that you get at your wall outlet. The circuits inside your computer would disappear in a flash if utility power got to them, however. They require a special diet, one that the infrastructure of your computer must create for them.

The power supply inside your computer converts utility power into a form that's safe for computer circuitry . The infrastructure of your computer distributes this power, both to the motherboard and to the various disk drives you install inside your computer.