People who have color deficiencies can actually see color. It is very rare for anyone to only see in black and white. There are different degrees in the severity of color deficiencies that a person can have, which can affect daily life. Some people have very minor color problems, and they do not affect their life. Others have severe color deficiencies which prohibit them from doing certain jobs or hobbies.
The retina inside the eye is made of cells shaped like Rods and Cones. Cones see color and rods detect the white to grey spectrum. There are three different cones, one that detects red, the other green, and the last sees blue. If there are less of a particular cone, then the perception of color is not consistent to what other people see. This person would have a color deficiency.
The most common color deficiency is the Red-Green deficiency. This affects males much more than females due to genetics. The bad gene usually skips generations and stays with the men. Women can still be affected, but it would mean that their mother was a carrier of the gene, and their father was also color blind. RG color problem affect 1 in 20 males, and around 1 in 200 women.
The second most common is the Blue-Yellow deficiency. This disorder is rare and affects men and women equally at 1 in 10,000. The name is misleading because people with this disorder will not confuse blue and yellow, but they will confuse blue with green and yellow with violet. You can actually acquire this color deficiency from certain chemicals, drugs, head trauma, or alcohol abuse.
If you have a color deficiency it won’t really affect your quality of life, but it could prohibit you from certain professions. You cannot fly a plane, because the controls and landing lights are often red and green. One could not be an electrician, due to needing to tell the wires apart from each other. You could drive a car, even though the lights are red and green, because you can still see what light is lit up. If you would like to see what color vision deficiencies are like, there are many example photos online that you can experience.