I have never even taken a sip of whisky.
It is a strong distilled alcohol made from fermented grain marsh.
Are there different kinds?
There are many different classes and types.
What kind of classes?  Never hear of them.
Different grains such as corn, rye, and wheat can be used and that is where the different classes and types come from.
Oh, how cool.  I imagine they all have different tastes then?
Whisky is usually aged in wooden casks, generally made of charred white oak, but can be aged in other types of wood barrels to get different flavoring also.