What is color separation?

Color separation is the process of separating a colored graphic or photograph into its primary color components in preparation for printed reproduction. For example, to print a full color photo with an offset printing press, we would create four separate printing plates each accounting for one of the four basic printing inks (cyan, magenta, yellow, and black) needed to reproduce the image.
As the paper is fed through the press, each single-color plate puts onto the paper the exact amount of ink needed at exactly the right spot. As the different colored wet inks are applied, they blend together to create the rich and infinite pallet of complex colors needed to reproduce the original image.