In short the entire concept/belief about chakras is a very old and complex one. It stems from the Vedas, which is one of the foundations of the Hindu religion. Chakra comes from the Sanskrit word cakra चक्र meaning "wheel, circle". Chakras are believed to be energy spots, nodes, pools, within the human body -- of which there are seven basic ones.
Now the more new-agey, foo-foo, folks have run rampant with what a chakra is, or isn't, etc, etc., etc. I'm telling you the historical basis of that!
Here is a pretty good page on this topic:
http://mailerindia.com/hindu/veda/in...p?kundalinipub
Hope this helps you out.