Color is the element of art that is produced when light, striking an object, is reflected back to the eye: that's the objective definition. But in art design, color has a slew of attributes which are primarily subjective. Those include characteristics such as harmony — when two or more colors are brought together and produce a satisfying effective response; and temperature — a blue is considered warm or cool depending on whether it leans towards purple or green and a red whether it leans towards yellow or blue.