Color palettes for web sites, posters, flyers, etc., are built from the twelve primary, secondary, and tertiary colors, also called the twelve purest hues. The primary colors for graphic design are red, yellow, and blue. These are not the same as RGB colors (red, green, blue) which are optimized for computer monitors. The secondary colors, or hues are: orange, green, and purple. Orange is produced by combining red and yellow. Green is a combination of red blue. Purple is made by combining red and blue.
There are six tertiary colors:
A graphic designer can produce millions of color combinations by combining these twelve colors.