A DC motor controller is an electronic device that regulates the speed and direction of a DC motor. It adjusts the voltage and current supplied to the motor, allowing for precise control over its performance. This is essential in applications where varying speeds or directional changes are needed, such as in robotics or electric vehicles. Typically, a DC motor controller uses techniques like pulse-width modulation (PWM) to efficiently manage power delivery. By rapidly switching the power on and off, it can control the average voltage and current reaching the motor. This results in smoother operation and improved energy efficiency.