Light (both natural and otherwise) is an essential tool in photography - here's a gallery dedicated to light use in photos, including low-light photography, black and white available light photos, night and morning photos.
Musical Harmony
© Heather K. McFarlandGazing Into Her Eyes
© Michelle CampbellSpin,Spinning,Spun
© Lyndel ReeseA Summer's Nite
© Kathy HarrisSunset on Sedona (AZ) Red Rocks with Moon
© Light _girl behind glass block
© Tom W. Hauber