The electricity produced by a generator travels along cables to a transformer, which changes electricity from low voltage to high voltage. Electricity can be moved long distances more efficiently using high voltage. Transmission lines are used to carry the electricity to a substation. Substations have transformers that change the high-voltage electricity into lower-voltage electricity. From the substation, distribution lines carry the electricity to homes, offices and factories, which require low-voltage electricity.

Source: Energy Information Administration