Pulse Width Modulation (PWM) is a technique used to control the amount of power delivered to electrical devices. It works by varying the width of the pulses in a signal while keeping the frequency constant. By changing the duration of the "on" time versus the "off" time, PWM can effectively adjust the average voltage and power supplied to a device, such as a motor or LED. This method is widely used in various applications, including motor speed control, light dimming, and signal modulation. PWM is efficient because it minimizes energy loss, making it a popular choice in modern electronics and power management systems.