An AC circuit is an electrical circuit that uses alternating current, where the flow of electric charge periodically reverses direction. This type of current is commonly found in household power supplies, allowing appliances to operate efficiently. The voltage in an AC circuit also varies sinusoidally, which means it follows a wave-like pattern over time. AC circuits can be classified into two main types: series circuits and parallel circuits. In a series circuit, components are connected end-to-end, while in a parallel circuit, components are connected across the same voltage source. Understanding these configurations helps in analyzing how electricity flows and how devices function within the circuit.