White Balance
Unless you've trained your eyes to do so, you may not notice the differences in the color of light in differing situations. But different light sources actually have different "color temperatues." Indoor lighting varies in color temperature--tungsten lights are redder than fluorescent. The above photograph was lit entirely by my daughter's night light--look how red the tungsten light looks on her face. Outdoors, the color of sunlight will change based on the amount of cloud cover and even the time of day. Most of us go through life blissfully unaware of this unless we're impacted by the beauty of a sunrise or sunset and notice that the colors we see then aren't the same as what we see during the day. A pure white object will have a different color cast when lit by different kinds of light (like my daughter's pacifier in the above photo lit by a tungsten night light). "White balance" allows you to correct for light of different color temp...