What is the difference between the RGB and CMYK color format?

RGB refers to the primary colors of light, Red, Green and Blue. RGB is the standard format used for video monitors, television screens, digital cameras and scanners. CMYK refers to the primary colors of ink pigment: Cyan, Magenta, Yellow, and Black. These are the ink colors used in "4-color process printing", commonly referred to as "full color printing". RGB and CYMK are not compatible formats. RGB files must be converted to CYMK before printing can occur. It is physically impossible for a printing press to exactly reproduce colors as seen on a computer monitor.