Additive color, what computers use, are created with light. It begins with black and ends with white; as more color is added the result is lighter and tends to white. Red, green and blue are light primaries and percentages of these primaries are used to generate color on a computer screen.
It’s important to know that the visible spectrum consists of billions of colors, a monitor can display millions, a high quality printer is only capable of producing thousands and older computer systems may be limited to 216 cross-platform colors.
Reproducing color can be problematic with regard to printed, digital media because what we see is not completely possible to get. Although a monitor may be able to display ‘true color’ (16,000,000 colors), millions of these colors are outside of the spectrum available to printers. Since digital designs are generated using the RGB color system, colors used in those designs must be part of the CMYK spectrum or they will not be reproduced with proper color rendering. Working within the CMYK color system, or choosing colors from Pantone© palettes insures proper color rendering.