An RC circuit is an electrical circuit that consists of a resistor (R) and a capacitor (C) connected in series or parallel. It is commonly used in various applications, such as filtering signals and timing operations. The resistor controls the flow of current, while the capacitor stores and releases electrical energy. When a voltage is applied to an RC circuit, the capacitor charges through the resistor, and the rate of charging is determined by the time constant, which is the product of resistance and capacitance (τ = R × C). This behavior is essential in applications like smoothing out voltage fluctuations and creating delays in electronic devices.