The electromagnetic spectrum is made up of seven different kinds of radiation. They include, from lowest energy to highest energy: radio, microwaves, infrared, visible, ultraviolet, X-rays and gamma rays. The energy of the electromagnetic spectrum is measured by wavelength.
Visible light is composed of the wavelengths of energy ranging from 390 and 750 billionths of a meter. We perceive visible light in the form of color, while ultraviolet and infrared light, which bookend visible light, can be perceived with the aid of technology.
Visible colors in the electromagnetic light spectrum from shortest to longest wavelength are violet, blue, green, yellow, orange and red. White light is a mixture of all the colors on the visible spectrum, while black is the absence of light.