Color blindness is some sort of color vision deficiency which results in differences in the way that an affected person sees and distinguishes various colors. It is mostly inherited, but can also be caused due to damage to the eye, nerve, or brain. There is no proven way to change these vision deficiencies. When a color-blind user looks at a PowerPoint slide, he or she might view it differently than other people. Even different color blind users may not see the same slide with the same vision — there are three known varieties of color-blind visions.