absolute refrences

i just finished watching the second tutorial for excel 07 and it has reviewed for me a lot of what we have learned in class. the tutorial refreshed my memory of of the "auto-sum" function which is probably the most commonly used function in excel. but what i learned the most from the tutorial was the use of absolute references. how to keep a specific cell constant even when using the fill handle. it is an important feature to understand in order to master excel. i feel like i have only scratched the surface to understanding the use of absolute references and i can't wait to learn a lot more about how to use them.