Radiant energy refers to the energy of electromagnetic radiation. Since all EM radiation is photon-based, radiant energy is the energy carried by the relevant photons. Radiating bodies have typical portions of the electromagnetic spectrum in which their radiation is concentrated. Such radiating bands may be sharply defined, such as is seen in star spectra, or may be more diffused.

EM radiation has three principal components: wavelength and frequency, which are strictly inversely proportional, and intensity, which determines the amount of energy carried by the radiation. Radiant energy may be originated in a body or reflected from another body (in which case it may be refracted or otherwise modified).

In home heating applications, radiant energy is differentiated from convective and conductive energy.

See also

• Science: Power, Blackbody, Radiometry, Cosmic microwave background radiation, Cosmic background radiation, X-ray, Dirac sea, Photoelectric effect, Free energy, Perpetual motion, Schumann resonance, Open system, Teleforce
• Radio: Shortwave radiation, Longwave radiation, Federal Standard 1037C, Transmission, Telephone
• People: Nikola Tesla
• Other: Ark of the Covenant, Greenhouse gas, Geostationary Operational Environmental Satellite