Some examples of radiant energy are visible light, infrared and ultraviolet electromagnetic waves, radio waves and microwaves, and radiant energy's uses include heating, lighting and communications. All radiant energy is a form of electromagnetic radiation and its primary source is the sun, but it can also be produced by manmade methods. Radiant energy can be viewed as either a stream of photons or as an oscillating electromagnetic wave carrying energy in its changing magnetic and electrical fields.
The term "radiant energy" can be used to describe the energy carried by any form of electromagnetic radiation and is usually used when this form of radiation is emitted from an energy source into its surrounding environment. This energy can be visible or invisible to the naked eye, and it may or may not be felt by humans depending upon its frequency and amplitude. Radiant energy is one of the means by which energy can leave or enter either a manmade or a natural open system.