An Electrical Plug Connects to the Home Electrical Wiring
The color in a standard 3-prong plug are black (for the live wire), white (for the neutral wire) and green (for the ground wire). Standard 2-prong (non-grounded) outlets use the same colors but do not have a ground wire. The color-coded wires protruding from the plug are connected to the wires of corresponding colors in the home's wiring using either commercial-grade electrical connections or small plastic connectors known as "caps."
Plugs Are Secured in the Wall
Once the plug's wires are connected to the home wiring, the plug must be firmly secured in the wall. Most plugs are placed into a recessed metal housing; if no housing already exists in the wall where the plug is to be installed, these housings are inexpensively available at most home improvement stores. The housings also offer two small screw holes that are designed to accept screws passed through a plastic (or, in some cases, metal or pewter) cover, which is attached to the outward-facing surface of the housing for aesthetic purposes. These covers conceal the internal workings of the plug while also hiding the recess in where the plug is contained.
Plugs Conduct Electricity
With the plug properly wired and secured in the wall, appliances, lamps, electronics or other items requiring electric power can be plugged into the outlet. When the male metal prongs of the plug are inserted into the plastic-covered (but metal inside) female outlet, a conductive connection is created between the appliance or electronic and the home's electrical wiring. This connection allows electricity to pass freely from the electrical wiring into the item, providing the requisite power for the appliance or electronic to function.