I'm sure people may look at this question and be shocked at it's stupidity, but I'm very confused, so I feel the need to ask:
What is the difference between Continental's F class, J, C, D, and Z classes besides for the fact that they are all different prices? And why is it that on a given flight, there are no longer Z class available (as in they're sold out because it IS available on the same flight but different date) but there are C, D, J, and F seats available? If they're all in the same cabin, why does it matter? Furthermore, what exactly is A class as Continental sometimes seem to mention it, but it doesn't seem to ever be posted?

Thanks!!