PWM (Pulse Width Modulation) is a technique used to control the amount of power delivered to electrical devices. It works by turning a signal on and off at a high frequency, varying the duration of the "on" time compared to the "off" time. This ratio, known as the duty cycle, determines the effective voltage and power supplied to the device. PWM is commonly used in applications like motor speed control, LED dimming, and heating elements. By adjusting the duty cycle, users can achieve precise control over the performance of these devices while maintaining energy efficiency.