The page as a whole should look soothing and harmonious, with no more than a few color accents. A low-contrast pair such as yellow and orange or red and blue are difficult to read and cause eye fatigue. If you are using a textured background for text, the background should be relatively neutral and barely noticable . Complex backgrounds are OK for title pages and other displays which are seen only briefly, but should never be used for extensive text display. A common color scheme can be used to unify a group of pages, making it visually clear that they all belong to the same site.
Color can code information .
It is essential that the coding scheme be consistent, and that the user understand it.