Blue is one of the three primary pigments, along with red and yellow, and one of the three main colors of light along with red and green. With pigments, such as with paint, blue is combined with yellow to make green, or with red to make purple.
In US politics, blue is the color of the Democrats. It is sometimes associate with wealth, such as in the terms blue blood and blue chip. Elsewhere in the world the colour blue represents conservatism.