Color theory is a framework that explains how colors interact and the effects they have on human perception. It is based on the color wheel, which organizes colors into primary, secondary, and tertiary categories. Primary colors, such as red, blue, and yellow, can be mixed to create secondary colors like green, orange, and purple. Additionally, color theory explores concepts like complementary colors, which are opposite each other on the color wheel, and analogous colors, which are next to each other. Understanding these relationships helps artists, designers, and marketers create visually appealing compositions and convey specific emotions through color.