electromagnetic radiation

Electromagnetic influences (in the language of physics: electric and magnetic field) which, even with no electric charges present, are locked in a state of mutual excitation so that they form a wave that propagates through space.

As this wave transports energy, it is, by the usual physics definition, a form of radiation, called electromagnetic radiation.

Depending on frequency, there are special names for different types of electromagnetic radiation; going from lower to higher frequencies: radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.

In the context of quantum theory, it turns out that electromagnetic radiation consists of tiny energy packets, called light particles or photons.