An RL circuit is an electrical circuit that consists of a resistor (R) and an inductor (L) connected in series or parallel. The resistor limits the flow of electric current, while the inductor stores energy in a magnetic field when current passes through it. This combination allows the circuit to respond to changes in current over time. When an RL circuit is powered, the current does not instantly reach its maximum value due to the inductor's opposition to changes in current. Instead, it gradually increases, following an exponential curve. This behavior is essential in various applications, including filters and oscillators.