This is the coldest color. Blue is so pure that it is usually associated with ocean, sky, water and universe. Pure blue shows a kind of beauty, calmness, reason, tranquility and vastness. Blue has a rational and accurate image because of its calm characteristics. In commercial design, most commodities or corporate images that emphasize technology and efficiency choose blue as the standard color and corporate color, such as computers, cars, photocopiers and photographic equipment. In addition, blue also represents melancholy, which is influenced by western culture, and this image is also used in literary works or emotional commercial design.