The Electromagnetic (EM) Spectrum is a name scientists use for a group of radiation waves, energy that travels and spreads out as it goes. This can include: Visible light from house lamps, waves from a radio station, EM radiation from microvaes, ultraviolet light, gamma rays, x-rays, and so on. Electromagnetic waves can be described by their wavelength, energy, and frequency. All three are related to each other mathematically (e.g., energy of an X-ray, or the wavelength of a microwave, or the frequency of a radio wave). The electromagnetic spectrum includes, from longest wavelength to shortest: radio waves, microwaves, infrared, optical, ultraviolet, X-rays, and gamma-rays. (The Electromagnetic Spectrum. NASA.)

Electromagnetic radiation, part of the electromagnetic spectrum, are invisible forces that impact every facet of biological regulation and include: microwaves, radio frequencies, visible light spectrum, extremely low frequencies, acoustic frequencies, and scalar energy. (Lipton, Bruce H., PhD. The Biology of Belief. CA: Mountain of Love / Elite Books, 2005, pp 111-112)