Well, I guess to get down to the basic, basic on bipolar...it is a mood disorder that is characterized by extreme highs and lows. The intesity and frequentcy varies with each episode and each person. Each end of the polar is more extreme than what the "normal" person experiences and these mood changes can happen quickly for some people.
There is actually a list of criteria one must meet to be dx as bipolar but the mood changes are the core to the illness. I suggest you google some sites to read fo the various symptoms.
Have you been dx bipolar?
Bipolar is a very complicated disorder that diagnosticians try to break down into neat categories that don't hold up all that well. I've studied it at some length, my father has had it my entire life, my older sister has it, and I very recently was diagnosed.
My first question to you would be-- why do you think you have it? I think it makes more sense to go from there than to tell you all kinds of info about all different disorders related to bipolar.
I would also advise you to see a psychotherapist because the sooner bipolar is diagnosed and a treatment plan is begun, the better the prognosis. If you're in doubt, go ahead and check in with a doctor (if you haven't already).