Color should be used limitedly and when used should be checked to make sure it meets the needed color contrast ratios requirements.

When Using Color, You Should:

• Not use it by itself to distinguish something important
  • If the color is to signify that it is important make sure to make it bold, italics, add a border, or add asterisks (*) to the item so that users know that it is important.
• When using color in a graph/chart add a pattern as well to the item so that it is easily distinguished from the other pieces of the data
• Make sure that it passes the color contrast requirements
  • WebAim Color Contrast Checker

Some Specific Types of Color Blindness:

• Red-Green Color Blindness – most common color blindness
  • Deuteranomaly: Greens look more like red
  • Protanomaly: Reds look more like green but less bright
  • Protanopia and Deuteranopia: Greens and Reds look the exact same
• Blue-Yellow Color Blindness
  • Tritanomaly: Difficult to tell the difference between blue and green and yellow and red
  • Tritanopia: Cannot distinguish the difference between blue and green, purple and red, and yellow and pink. Colors also seem less bright.
• Monochromacy
  • Cannot see any color at all and see things in gray scale.
• Tetrachromacy
  • Can see more colors than the average person – note this impacts roughly 12% of women

Color Combinations to Avoid:

• Red & Green
• Green & Bran
• Green & Blue
• Blue & Gray
• Blue & Purple
• Green & Gray
• Green & Black