In the world of Errors..;

Red (R), green (G), and blue (B) are called primary colors. Mixing two primary colors creates the secondary colors cyan (G + B), magenta (R + B) and yellow (R + G). You saw these colors in the Complementary Colors challenge. These secondary colors happen to be the complement to the primary color not used in their creation, and are opposite to that primary color on the color wheel.  example : magenta is made with red and blue, and is the complement to green. Tertiary colors are the result of combining a primary color with one of its secondary color neighbors. example:  red (primary) and yellow (secondary) make orange. This adds six more colors to a simple color wheel for a total of twelve.

    The  wheel is a useful tool to visualize how colors relate to each other - it's a circle where similar hues are neighbors and different hues are farther apart. When two colors are opposite each other on the wheel, they are called complementary colors. They have the characteristic that if they are combined, they "cancel" each other out and create a gray colour. However, when placed side-by-side, these colors appear more vibrant and produce a strong visual contrast. example: red (#FF0000) and cyan (#00FFFF) green (#00FF00) and magenta (#FF00FF) blue (#0000FF) and yellow (#FFFF00)