An essential part of understanding color is knowing what light is. Light is electromagnetic energy which is radiated as waves. The wavelength of these waves is the distance between one peak of such a wave to the next peak. Humans are generally capable of seeing wavelengths from as short as 400nm (violet light) to as long as 700nm (red light). This part of the electromagnetic spectrum is called the visible spectrum. What color we see is depending on which combination of wavelengths reaches our eye. For more information on color perception see our spectrum page.