PCApex has a new article up covering the basics of how heatsinks work as part of a series of upcoming "basics" articles to help educate those not already in the know. This series of articles is intended to help inform the many n00b g33ks out there. Here is a snip from the article:
"Heat is actually molecular vibrations in any material and our fingers interpret this vibration as heat. The greater the vibration, the hotter the material is/feels. In order to cool down the material these vibrations need to be dispersed or thinned-out in some way. If you have ever played with a tuning fork, try to think of when you would strike it and let it stop vibrating on its own. If you were to touch the fork, your finger would absorb the vibrations and the humming would stop along with the vibration. This is a very very general example of what your CPU cooler does. It takes the heat (molecular vibrations) generated by your PC's CPU and disperses it in order to keep the CPU cool and prevent any heat build up which could kill your processor."