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.
Tired Flower Girl
© Michelle CampbellPensive
© Kenneth J. GimmiPre-dawn Christmas Decorations
© Light _Family again
© Michelle CampbellKings of the Mountain!
© Juliane Morris-LuskMS-1793
© Jim Zuckerman