Creatine?

Do anyone know where to find the best creatine supplement? one of my friend is looking for this supplement. I am taking iron and calcium supplement right now, but my friend said, creatine is not bad. But then again, I do not know what is Creatine. Maybe I should Google and check whether Creatine is a good supplement for me or not. If it is as good as what my friend told me about, I think I will consider taking is as supplement.