Individual demand is the amount of a product an individual (or single buyer) is willing to purchase with his or her limited income at the prevailing set of relative prices over a specified period of time.
Have you ever been shopping and chose to purchase an item your friends did not purchase? Perhaps you did not buy something because you could not afford it. The price is the same, so why did your behavior differ from your friend's. One answer is that you have different individual demand curves. All of us have an individual demand for every good or service. The slope and quantity demanded at each price depend upon the individual's personal circumstances.