CMYK means C = cyan, M = magenta, Y = yellow, and K = key (or black) is the color model used in most prints.
It's also referred to as an abstract color model, and if you do not understand what this means or how it works, the following excellent demonstration will help you understand it.
The video shows how each subsequent color after black and white subtracts luminance from the background to create the final color of image. In the model CMYK, all the colors together overlap to finally create black, compared to the RGB prosthetic model where white is the result of the combination R = red, G = green, and B = blue (red - green - blue).
In the video you will see 4 pieces of glass that, if you place them on top of each other, Vermeer's painting "Girl with a Pearl Earring" emerges in color. The video certainly is advertising selling these tiles as coasters, it is still a very good example for those who want to learn about color analysis and digital color imaging.
Watch the video below:
https://www.youtube.com/watch?v=3j4GCRH9w7o
