Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths discernible by the human eye, in the wavelength range of roughly 630–740 nm. Longer wavelengths just past this range are called infrared (below red) and cannot be seen by the naked eye although they can be sensed as heat. In some cultures, certain shades of red are used to symbolize anger or aggression.

It is the color of blood when it is exposed to sunlight, and it is most commonly referred to as a color of evil, love, and sometimes, though rarely, happiness.