This is all that we mean by the law of demand. A Demand Curve is a graphical depiction of the law of demand. We plot price on the vertical axis and quantity demanded on the horizontal axis. The demand curve has a negative slope as the law of demand suggests. The Law of Supply and the Supply Curve Supply is a little more difficult to understand because most of us have little experience on the supply side of the market.
Supply is derived from producers' desire to maximize profits.
When the price of a product rises, the supplier will have an incentive to increase production because he can justify higher costs to produce the product, and there is increased potential to earn a high profit margin. The Law of Supply holds that other things equal, as the price of a good rises, its quantity supplied will rise, and vice versa. A Supply Curve is a graphical depiction of a supply schedule plotting price on the vertical axis and quantity supplied on the horizontal axis. The supply curve is upward-sloping, reflecting the law of supply. The market supply curve is derived by horizontally summing each individual's supply curve.