Many people are certain that they perceive light in one way: bright! It's often not until operating a camera or mechanical device without using the white balance feature that we realize light sources have dramatically different color casts on different subjects. The human eye often compensates a bit for this difference, but even so, a light bulb with the correct color temperature can make a profound difference in the appearance of a stage, an art gallery, or a room. Color temperature is a concept that both relates to the temperature of the light source and the intensity as a black body radiator.
Visible light falls into the electromagnetic spectrum, and represents waves from 400 to 700 nanometers. While many other aspects of light in this spectrum remain the same, such as the speed of light, the color changes depending on where on the spectrum it is. The color temperature of most common light sources range between 6,000 and 3,000 degrees Kelvin. A higher amount of degrees relates to a bluer cast, and a lower degree can create a redder cast. The flame for a light or a candle is typically between 1,500 K and 2,000 K, whereas daylight is typically around 5,700 (though it ranges during the day). Different light bulbs can cast different color temperatures; for instance, photographers and videographers know that florescent bulbs result in a blue tint to their final products, and that incandescent bulbs are warmer in color. When buying bulbs, find out your target color temperature range, and shop for results within your range. For a work space, you may want to shop for a light that has a color temperature that's closer to daylight.
Use the resources below to learn about what color temperature is, and why it's a film director's and interior decorator's best friend: