The Contrast Ratio of a TFT is basically the difference between the darkest black and the brightest white. As a rule of thumb, the higher the contrast ratio, the better. The higher the contrast ratio, the stronger the colours will look. The depth of blacks and the brightness of the whites are also better with a higher contrast ratio. When considering a TFT monitor, a contrast ratio of 500:1 is pretty standard nowadays, but there are models which boast specs up to over 1000:1. Be wary of quoted specs however, as sometimes they can be exaggerated. VA panel specs are generally the most reliable and accurate to reality when considering contrast ratio.