Alternating current (AC) electricity is the type of electricity most commonly used in homes and businesses all over the world. It is said to “alternate” because it reverses direction in an electrical circuit at regular intervals, usually many times per second. Alternating current is created by an electric generator, which determines the frequency of these oscillations. In the United States, alternating current is generated at 60 hertz, meaning that the current alternates 60 times per second.