From school physics I recall the following means by which heat spreads out: conductance (particles bump against each other), radiation and the original heated mass moving (for example: sea currents).
Electromagnetic radiation heats things. For example: sunlight and infrared sauna.
Given these two hopefully correct recollections it would be tempting to say that all heat radiation is in fact electromagnetic radiation. Is this so and what is the mechanism behind such radiation appearing? Is the radiation concentrated around certain wave lengths (such as infrared) or distributed among different wave lengths in some other notable way?