You guys might remember from science class that your eyes have these things called photoreceptors. There are two types of photoreceptors in the eye, the rods and the cones. When your cones lack certain pigments, you can get the most common type of colorblindness, which is a red-green color deficiency.
So, let's say you were color deficient. I bet you would be a guy, because most color blindness is inherited and is X-linked recessive. That means guys will much more commonly have a color deficiency than girls. See how cool it is to be a girl? Girls rock. About 8% of men and 0.5% of women have some form of color deficiency.
To find out a little more about color deficient individuals, I text-interviewed my friend who is colorblind. He found out he was colorblind in elementary school. He claims to be good at identifying bold, solid colors, but has trouble distinguishing shades. My colorblind friend also said that his maternal grandfather was also colorblind (see, X-linked recessive). He said he has adapted very well to his color deficiency, but sometimes flashing yellow or red lights when driving can be a problem.
Unfortunately, there is no cure or treatment for colorblindness. There is tinted contact lens that can be used to pass the colorblindness tests, but it does not cure colorblindness or serve any purpose other than test-passing. Speaking of tests, one of the most common is a book full of colored pictures that looks like a number to people without color deficiency. They are called Ishihara plates, named after the cool Japanese dude that invented them. There is also a test called the D-15, that involves putting colors in order, kind of like a rainbow. Here are pictures:
The bright side of colorblindness: People who are colorblind are better at seeing camouflage than people with normal color vision. So don't try to hide in camo around your color-deficient friends, they will find your ass. Also, people who are colorblind are able to adapt very well to picking up non-color cues to help them out. They are awesome, wonderful people.
So, as the summer comes to a close, remember to be thankful for this beautiful, colorful world we live in. Have a fantastic day!