Primary And Secondary Colors

The basic colors of the RGB and CMY models are called primary colors.
When mixing two primary colors, we obtain the secondary colors. orange, e.g., is a secondary color because it is mixed from red and yellow.
And finally, we obtain the so-called tertiary colors when mixing components of all primary colors.
The following color bands demonstrate the vast array of secondary colors. The extremes of the color bands represent the basic colors of the RGB-model, namely red, green and blue; the centers of the bands represent the derived colors of the RGB-model, namely yellow, cyan and magenta. All colors situated between the center of a band and one of its two extremes are secondary colors:

From red via yellow to green

From green via cyan to blue

From blue via magenta to red