The Electromagnetic Spectrum is a whole picture or a log of all the energy frequencies observed by scientists thus far. It is called "electromagnetic" (EM) because energy has both an electrical and magnetic component. The EM Spectrum then is a description of energy frequencies from a few cycles per second to several million cycles per second. A vibration is made up of energy pulsations of positive and negative polarity. We call that "frequency." Low frequencies, for example, describe the electrical energy of brainwaves. A few hundred cycles per second is what we call sound; a few thousand cycles per second are radio waves, and several million cycles per second are called light. So, from sound to light there is a very broad range of frequencies. Vibrations in matter give us audible sound. Vibrations in the ether give us heat, light ultraviolet rays, x-rays and radio. Color is simply a specific light frequency. Subtle energy and thought vibrations are known as Scalar Energy and could be considered a 4th dimensional component of every 3rd dimensional vibration. Valerie Hunt's "The Science of Human Vibrations," describes the aura as containing millions of harmonic frequencies that gently penetrate the body through the skin.