Go Mediazine: Rule Three: Contrast, Contrast, Contrast

http://www.gomediazine.com/design-tip/rule-three-contrast-contrast-contrast/
"Good contrast in your design goes hand-in-hand with your color selections. Contrast is the value difference between the colors on your design. Value is how bright or dark the color (ink) is. Ever see a blank white canvas and as a joke someone says: “Hey – it’s a white cow in a snow storm!” This is an example of no contrast. White on white is no contrast – you can’t see anything."