Leading and Trailing Edge definition/explanation

Leading and Trailing edge are types of dimmers. Leading edge dimmers were originally used for dimming incandescent and halogen lamps. Because of this, they have a high minimum load which makes them less useful for low energy lighting such as LEDs.

Trailing edge dimmers have many more benefits, including reduced buzzing and smoother dimming, They also have a lower minimum load, making them more suitable for lower energy lighting including LEDs.