Why would the color on your monitor and the color on the actual postcard vary? Simply because they use different methods for creating color. There are differences between what you see on your computer screen and the output of your color printer. In some cases, they can be quite different. The color displayed on your computer monitor is created by projected or additive light. Red, Green, and Blue lights (hence the term RGB) are projected in differing strengths to form various color combinations. White results from combining Red, Green, and Blue at full strength. Printed color, however, is reflected or subtractive color. The printed inks absorb (subtract) certain colors from the visible light spectrum -- what you see is actually the light that is reflected off the printed matter (paper and inks). Printed color is referred to as CMYK color because Cyan, Magenta, Yellow, and Black inks are used to create the colors.