Color blindness is "the inability or decreased ability to see color, or perceive color differences, under normal lighting conditions." Vibrant colors become black and white and trying to figure out a stoplight can become a pain. It can be caused by physical or chemical damage to the eye, optic nerve, or areas of the brain, and it can also be hereditary.
Luckily, there's an upside. Color blind people tend to have better night vision and can sometimes see luminosity of colors that normal-sighted people can't. With this ability, and the fact that they perceptive colors differently, the U.S. Army discovered that the colorblind could see 'camouflage' colors that are hard to see with normal color vision. This gives them the unique ability to see hidden enemies better at night.
