Alternating current (AC) is a type of electrical current that periodically reverses direction. Unlike direct current (DC), where the flow of electricity is constant and unidirectional, AC changes its polarity, allowing it to flow in both directions. This characteristic makes AC suitable for powering homes and businesses, as it can be easily transformed to different voltages. AC is generated by devices such as generators and is commonly used in power grids to distribute electricity over long distances. The frequency of AC, measured in hertz (Hz), indicates how many times the current changes direction per second, with 60 Hz being standard in many countries, including the United States.