Demand, how much people desire said product. The law of demand states that price and quantity demanded are inversely related. In other words, as one goes up, the other goes down. Which makes sense to me in that if chocolate is expensive, you will buy less of it. Or if chocolate is only a dime per bar, you might as well buy ten for a dollar, and in doing so increase the quantity demanded. As for the reality of things, a dime per chocolate bar will only exist in my wishful thinking.