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.
A quiet moment
© Kathy HarrisLife, Liberty and the Pursuit of Happiness
© Patricia MarroquinPractice Makes Perfect
© Michelle CampbellAnother Close Up
© Michelle CampbellLonely Light
© Kerry Drager