Electromagnetic fields have been around in different forms since the birth of the universe. They differ from each other by frequency and visible light is its most familiar form.Electric and magnetic fields are part of the electromagnetic spectrum which extends from static electric and magnetic fields, through radio frequency (RF), infrared radiation, and visible light to X and gamma-rays. The purpose of the EMF Guide is to provide information and education resources on Electromagnetic Fields.

http://emfguide.itu.int/emfguide.html