What is color blindness?

Unable to see colors: People who are colorblind are unable to distinguish between certain colors. Most commonly it affects only certain colors, such as green and brown, but in some people other colors are also affected.

Color blindness: Color blindness is a congenital or acquired condition whereby a person cannot see certain colors well because the parts of the eye that receive those wavelengths of light do not function well. For example, some people are born with red=green color blindness. They cannot see the color red or green well. Those colors would look gray or "washed out". Special tests can determine color blindness.