Printing colors are composed of different percentages of C, M, Y, and K, hence the term "mixed colors" is appropriate. C, M, Y, and K are the commonly used four primary colors in printing.
Printing Machine - A machine used for printing text and images. Modern printing machines typically consist of components such as plate setting, inking, impression, and paper feeding (including folding). The working principle involves first creating a plate with the text and images to be printed, mounting it on the printing machine, then manually or automatically applying ink to the areas with text and images on the plate, and transferring it directly or indirectly onto paper or other substrates (such as textiles, metal plates, plastics, leather, wood, glass, and ceramics), thereby replicating the printed product identical to the plate.
During the printing of primary colors, each of these four colors has its own color plate, which records the dot patterns of that color. These dot patterns are generated by halftone screens. Combining the four color plates together forms the defined primary colors. Adjusting the size and spacing of the dots on the plates can create other primary colors. In reality, the four printing colors on paper are separate, but they are very close to each other. Due to the limitations of our eyes' resolution, we cannot distinguish them. Our visual impression is the mixed effect of various colors, which then produces different primary colors.
Y, M, C can produce almost any color, but black is still needed, as the black produced by Y, M, C is not pure, and pure black is required during printing. Moreover, using Y, M, C to create black can result in excessive ink in certain areas.
C、M、Y、K ：
Represent the four colors used in printing.
C stands for cyan, M for magenta, Y for yellow, and K for black.
In practical usage, it's challenging to blend blue, magenta, and yellow to produce a true black; the result is often a brownish hue. Hence, the introduction of K for black.
The black's role is to tone down, deepening the darker colors.