Mixing red and green together makes the color brown. The three primary colors are red, blue and yellow. Green is formed by mixing blue and yellow, and it is a secondary color.
The other two secondary colors are purple, formed by mixing red and blue, and orange, formed by mixing red and yellow. The tertiary colors are formed by mixing a primary color with an adjacent secondary color. The tertiary colors are blue-green, yellow-green, yellow-orange, red-orange, red-violet and blue-violet. Red and green are complementary colors, as are blue and orange and yellow and purple. Mixing two complementary colors results in brown.