what the colours mean.

Complementary colors are pairs of colors which, when combined in the right proportions, produce white or black.  When placed next to each other, they create the strongest contrast and reinforce each other. They are widely used in art and design. The pairs of complementary colors vary depending upon the color model, and how the color is made. In painting, which uses subtractive primary colours the traditional primary–secondary complementary color pairs, described since at least the early 18th century, were red-green, yellow-violet, and blue-orange. In the more accurate RGB colour model, used to make colors on computer and television displays, red, green and blue light are combined at various intensities to make all the other colors. In this system, using addictive colours, the complementary pairs are red–cyan, green–magenta, and blue–yellow. In color printing, another system of subtractive colors, the colors cyan, magenta, yellow and black are used to produce all printed colors; the CYMK- system complementary pairs are the same as in the RGB system: red–cyan, green–magenta, and blue–yellow.

Additive colour is colour created by mixing light of two or more different colours. Red, green and blue are the additive primary colours normally used in additive colour system. Additive colour is in contrast to subtractive colours in which colours are created by subtracting (absorbing) parts of the spectrum of light present in ordinary white light, by means of coloured pigment, or dyes, such as those in paints, inks, and the three dye layers in typical colour photographs on film. A subtractive colour model explains the mixing of a limited set of dyes inks paint pigments or natural colorants to create a wider range of colours each the result of partially or completely subtracting (that is, absorbing) some wavelengths of light and not others. The colour that a surface displays depends on which parts of the visible spectrum are not absorbed and therefore remain visible.