Every color, each with its own frequency, is a form of energy. The electromagnetic spectrum describes all kinds of light in the universe: gamma rays, x-rays, UV, infrared, microwaves and radio waves, many of which the human eye cannot see due to our biological limitations. Visible light is the part of the electromagnetic spectrum that is perceived by the cone shaped cells in the human eye- and it includes all of the colors we associate with a rainbow- red, orange, yellow, green, blue, indigo, and violet.