EMF stands for electromagnetic field (also called electromagnetic frequency or electromagnetic force). EMFs are invisible fields of energy produced by electrically charged objects. They exist on a spectrum ranging from extremely low frequency (ELF) fields — produced by power lines and household wiring — to radiofrequency (RF) radiation emitted by cell phones, WiFi routers, and cell towers, all the way up to X-rays and gamma rays. In common usage, “EMF” typically refers to non-ionizing radiation in the RF and ELF ranges, which are the types most people encounter in daily life from wireless devices and electronics.