Hi bwtr, Think of it as anti-light: the stronger it is, the less light there is. The animation above has the sphere "sucking in" light instead of giving it off like a light bulb would. "So, how would I use negative light?", you might ask yourself. Your imagination is the limit. However, it's usually used in environmental scenes or large indoor scenes to speed up creation of moods. For example, if you had a room with a table lamp in it that was very bright but discovered that it was lighting up the room to much, instead of fussing with fall-off rates and ambient light settings, you could simply throw in a couple of negative lights in the corner of the room to remove the unwanted light. Negative lights could also be used on a hooded character to hide the it's face - even if there was a bright light in front of it. Hope this helps! It's kind a goofy thing to start thinking about but has some very valuable applications.