Heat is electromagnetic radiation OR heat is __spread by__ electromagnetic radiation?

[bobobobo]

So heat is vibration of atoms in lattice (or fluid).

Heat is also electromagnetic radiation.

Do we say "heat is electromagnetic radiation", or is that incorrect, since heat is vibration of atoms in lattice?

Should we say "heat is __spread by__ electromagnetic radiation instead?

[Born2bwire]

I would say that electromagnetic radiation is one method of the transference of heat. There are other methods. Convection, conduction and radiation are the three classical methods of heat transfer.

[mugaliens]

Actually, heat is the energy transferred from body or system to another through "thermal contact," which includes all means of transferring thermal energy, including conduction, convection (which is really conduction through an intermediate fluid), and thermal radiation.

I think what you're talking about is "internal energy" of a system, of which there are several types. Here's a table (http://en.wikipedia.org/wiki/Heat#Internal_energy).