Color tells you something about how much and what kind of light is absorbed by a material. By absorbing more light, objects usually heat up more.

When light hits a material, there are three possibilities for what happens to it. The light can be reflected (bounces back), absorbed (stays inside), or transmitted (passes through).

For something that has a color from being painted, like a car, or dyed, like a t-shirt, seeing its color means that the object reflects that color and absorbs all other colors. (Typically, transmitted light is very small in these cases.) For example, you see a red shirt as red because it reflects red light back to your eye and absorbs all other colors of light.

Two special colors to think about are white and black. For white, the object is reflecting all visible colors. For black, the object is absorbing all visible colors. As a result of this, black-colored objects tend to heat up faster than white-colored objects of the same material.

An object with a color will reflect light of that color, and absorb light by other colors. White reflects all colors, and black absorbs all colors. Light is energy, and any light that is absorbed is converted into heat.