it illuminates only those parts of the rooms as required. The bulb has six distinct sections to it, and via the remote control you can change the brightness and direction of the lights. The theory is that we use many bulbs and light sources in a room and most of the time they are unnecessary. This one bulb can be powerful enough to illuminate the entire room or segments which light-up required areas only. On paper this sounds good, but some may prefer Full Enlightenment to partial lighting.