Electromagnetic radiation (EMR) is a stream of photons each traveling at the speed of light.
Photons are massless bundles of light energy. The higher the energy of photons the more they behave as particles and can be harmful. The symbol shown with what looks like three blades of a fan notifies you that the radiation in the area can be dangerous.
The Electromagnetic Spectrum ranks EMR from lowest energy/longest wavelength to highest energy/shortest wavelength.The highest energy includes x-rays and gamma rays.
Sunlight is EMR, but x-rays and gamma rays are not part of the sunlight reaching Earth’s surface. The three forms of EMR that makes up most of sunlight are in order from most to least energy, ultroviolet radiation (UV light), visible light, and infrared radiation (IR) or infrared light.
Find out more about EMR and other types of energy in “Janice VanCleave’s Energy for Every Kid.”