What the subject wants to ask is what does it mean that there are many s in the concept map of supply and demand? In economics, the demand curve is represented by D and the supply curve is represented by S, which originated from the English word demand and supply. Demand refers to demand and supply refers to supply. The demand curve shows the quantity of goods required at each price. Demand curve is a curve showing the relationship between price and demand, which refers to the table or curve of the quantity of goods that buyers are willing to buy at various price levels under the same other conditions. The demand curve can appear in any shape, and the demand curve that conforms to the demand theorem can only tilt to the lower right. The supply curve is a functional relationship between commodity price and supply expressed by geometric figures, and the supply curve is a curve drawn on the plane coordinate diagram according to the combination of commodity price and supply in the supply table. Generally speaking, supply will be positively related to price. The factors affecting supply include: the price of the commodity itself, the production cost, the technical level of production, the price of related commodities and the producer's expectation for the future.