Blue is a primary color, which means you cannot create it by mixing other colors. Blue does mix with other colors to create new colors, including mixing with yellow to make green and mixing with red to make violet.
The three primary colors are blue, red and yellow. All other colors come from mixing different intensities and combinations of the primary colors. Green, orange and purple are the secondary colors obtained by directly mixing even quantities of two primary colors. A primary and a secondary color combine to create the tertiary colors, such as yellow-orange, red-orange and blue-violet.
The color wheel developed by Sir Isaac Newton in 1666 presents colors in a logically organized arrangement of pure hues. It clearly shows the relationship between primary, secondary and tertiary colors and is an invaluable tool for artists, designers and decorators who focus on color harmonies.