The light we see is a form of energy called electromagnetic radiation. It may sound like something complicated, but it’s nothing too exotic or unfamiliar. Everything you see is because of electromagnetic radiation. Electromagnetic radiation consists of perpendicular electric and magnetic fields that oscillate in amplitude. The number of times per second that the fields oscillate is the frequency of the radiation. This is measured in Hertz (Hz), or inverse seconds. The wavelength is the distance that the light travels through space during one oscillation of the electric or magnetic field.