AC (engl. Alternating CurrentAlternating current) refers to an electric current whose direction and strength change periodically at regular intervals. Alternating current is therefore characterized by the continuous change in direction (polarity change) of the current and voltage values.
The term AC is also often used colloquially for "alternating current". Alternating Voltage) is used, whereby strictly speaking a distinction should be made between current (AC) and voltage (AV).
Alternating current is primarily used for energy transmission and distribution in the public power grid, as it is easier to transform, switch and transmit over long distances than direct current (DC). Important parameters of alternating current are frequency (e.g. 50 Hz in Europe), effective value and waveform (usually sinusoidal).