light is a form of electromagnetic radiation along with radio
waves, microwaves, infrared radiation, ultraviolet rays, X-rays, and
gamma rays. All electromagnetic radiation travels through space at the
speed of light, or 186,000 miles (300,000 km) per second.
The light we can see represents only a very small portion of the electromagnetic
spectrum. On one end of the spectrum are radio waves having wavelengths
billions of times longer than those of visible light. On the other end
of the spectrum are gamma rays, with wavelengths millions of times smaller
than those of visible light. Wavelength is directly related to the amount
of energy the waves carry. The shorter the radiation's wavelength, the
higher its energy.