I will not bore you with the what, why, who and how of Excel. here. If you are interested, please visit our friend Wikipedia's page here to know abut the details.
I will be trying to give my two bits of info about Excel related topics - mostly info that I have tried to gather when I was a student myself. I will try to make it as clear and concise as possible.
This may not be the only place where you can get this kind of info, but I will definitely try to make it one of the places where you would want to check first.
Hope this Helps.
P.S : If you want something in particular do send me a note either in comments of by way of "contact me" option in my profile. No Spamming Please.