This page contains a test about color blindness, sometimes called the color deficiency test. Color blindness occurs when there is a problem with the color-sensing materials (pigments) in certain nerve cells of the eye. These cells are called cones. They are found in the retina, the light-sensitive layer of tissue at the back of the inner eye. If you want, before taking the test you can read more about color blindness.
Warning: This is just a fun test, so don't take it seriously. If you get a bad score, this may not mean you are color blind. It could be that your monitor has color problems, or that your graphic card is not very high in resolution.