Is it some form of radiated energy?
I looked at:
http://scienceworld.wolfram.com/physics/Heat.html
but it didn’t really answer my question?
Well, that page, while summing up the first law of thermodynamics rather nicelly, tells you absolutely nothing about what heat is.
To put it simply, heat is thermal energy. It is important to realise that while temperature is a rather complex concept, heat is just the thermal energy of particles.
In order to get to the bottom of this, we have to look at a what experts call a very, very small scale. i.e. look at individual molecules. To make it easier, let us restrict ourselves to ideal monoatomic gasses. An ideal gas is a collection of monoatomic molecules, moving around at random in three dimensions. You may think of the molecules as small billiard balls, flying around at random, and colliding with each other.
You may remember from physics class, that the kinetic energy of a moving object is mv[sup]2[/sup]/2, but even if you don’t, it’s fairly obvious that the balls moving faster have higher energy.
As long as all this motion is random (i.e. there are as many molecules moving in all directions), this energy is called heat.
Basically that’s all there is to it. (As long as you restrict yourself to monoatomic ideal gasses.) By counting vibrational and rotational modes in the molecules, it is possible to look at polyatomic molecules, but in taking the step to looking at solids, we need to take into account the gitter structure of te solid, as well as freely moving electrons. That’s beyond the scope of this post.
The radiated energy you mention in the OP, is something almost unrelated. It is a property of every moving body with a temperature above absolute zero to radiate energy in the electromagnetical spectrum, but that is quite hard to understand from basic principles, and is often taken for given.
(If you want to know more about temperature, and how that relates to heat, I suggest you do a search here, or look at this, a very readable guide that purports to explain the difference between heat and temperature, in very simple language.)
I’m sorry, my Popup blocker blocked your response… could you repeat that ? 