Charged particles also absorb electromagnetic radiation. When they absorb the radiation the accelerate. Their random kinetic energy increases. In thermal equilibrium, the amount of energy they loose to radiation equals the amount of energy they gain from radiation. But hotter objects emit more radiation than they absorb from their cooler environment.
Radiation can therefore transport heat from a hotter to a cooler object.
Electromagnetic radiation refers to electromagnetic waves which travel through space with the speed of light. A wave is characterized by a wavelength. The wavelength is the distance from crest to crest or from trough to trough. We classify electromagnetic waves according to their wavelength. A graphical representation of the electromagnetic spectrum is shown in the figure below.