Alternating Current is an electric current that reverses direction at regular intervals.
In alternating current (AC), the flow of electric charge periodically reverses direction, whereas, in direct current (DC, also dc), the flow of electric charge is only in one order. AC and DC often mean simply alternating and straightforward, as when they modify current or voltage.
AC is the form in which electric power is delivered to businesses and residences. The usual waveform of an AC power circuit is a sine wave. In specific applications, different waveforms are used, such as triangular or square waves.
Audio and radio signals carried on electrical wires are also alternating currents. In these applications, an important goal is often to recover information encoded (or modulated) onto the AC signal.