Humans limitations and abilities in processing information varies. Different senses respond to information and receive the information. As everyone is slightly different in his/ her capabilities there are some general rules that apply to HCI. Therefore, the knowledge about the limitations and abilities of the brain, vision and auditory senses is crucial to develop satisfactory HCI in any design. As a web designer, I’m familiar with color limitations and human perception of the color. The good tool to use to evaluate the color contrast characteristics can be found here http://soap.stanford.edu/show.php?contentid=54 . The result shows if there is enough color difference and brightness in foreground and background colors. After reading the material I was surprised with racial differences in color deficiencies.