The Law of demand establishes the functional relationship between the Price of a commodity and the quantity of that commodity demanded at different prices, assuming other factors remaining constant.
When the price of a commodity rises, demand for it falls and when the price of the commodity falls, demand rises. So less quantity is demanded at higher prices and more quantity is demanded at lower prices. There exist inverse relationship between price and quantity demanded of a commodity.
Definition: -According to Marshall the law of demand, is defined as “Other things being equal, the quantity of a commodity demanded varies inversely with its price.”