PWM - Pulse Width Modulation with regards to LEDs means that the LEDs will be pulsed or strobed at a rate so fast that the eye will see the light as being constantly on. In fact it is not. This pulsing or turning the LEDs on and off lowers the potential heat stress on the chemical that makes the light, thus allowing the LEDs to perform longer than anticipated. This is why we strongly recommend a low voltage dimmer
with PWM component operated at 80% minimum, or that you purchase a LED product with on board PWM.