 To understand market demand, one should have understanding about individual demand. As far as demand by individual is concerned, it is willingness and ability to buy against different prices. In this diagram, we are reporting the demand by apples by an individual by taking quantity of apples on horizontal axis and price on vertical axis. And by looking at the curve, we can see there is a negative association between price and quantity of apples. And when we make discussion about the market demand, it is demand by all the individuals in a particular market. To keep things simple, we start by making an assumption, in that market there are only two individuals. One individual is Ahmed and other one is Zainab. If we look at the demand by Ahmed in the first part of the diagram, we can see again there is a negative association between price and quantity demand of apples. But for Ahmed, if price is 600 rupees, Ahmed is not willing to buy any unit of apples. But when we look at the demand of apples by Zainab, we can observe that if price is equal to 600 rupees, then Zainab is able to buy two units of apples. So by aggregating demand by Ahmed and Zainab, if price is equal to 600, we can report market demand. For example, in this particular case, if price is equal to 600, then demand in the market is equal to 2kg of apples by all the individuals in that particular market. And if there is a decrease in price of apples, we can see there is increase in demand by both Ahmed and Zainab. And if price becomes 100, then total demand in the market is equal to 14kg of apples. So by aggregating demand by Zainab and Ahmed, we can report market demand and market demand in fact is demand by all the individuals in a particular market. Whenever we make discussion about change in market demand, there are two types of the changes. We call one change as change in quantity demand and other one as change in demand. When we say change in quantity demand, it is because of change in price of that particular commodity. If price of commodity increases, then there is a decrease in quantity demand. And if price, if there is increase in price of the commodity, there is decrease in quantity demand of apples. And this movement along the demand curve is called as change in quantity demand. But it might be possible there is change in factors other than price in a particular market. When there is change in factors other than price, again there is change in demand. But this change in demand is called as this change in quantity demand is called as change in demand. So change in demand might be it might be possible there is increase in demand or there is decrease in demand. When we say demand curve shifts rightward, in fact it indicates an increase in demand. And if demand curve shifts leftward, the whole demand curve shifts from one position to another position then it indicates a decrease in demand. So elaborate the concept of change in quantity demand and change in demand, we are using this particular association between quantity of apples and price. In this diagram, you can observe if price is equal to PA, then quantity demand of apples is equal to QA. And when price of the commodity decreases from PA to PB, there is increase in quantity demand of apples. So the movement along the demand curve from point A to point B is called as increase in quantity demand of apples. But it might be possible there is change in factors other than price. Because of that change in factors other than price, demand curve will shift from one position to another position. And this movement from D1 to D2 is because of factors other than price. And in this particular case, if price remain constant k price of commodity is still PA, but consumer is willing to have QB quantity of apples that we are denoting by point C in D2 curve, it indicates increase in demand for apples by individuals. So the movement from point A to B is called as change in quantity demand, while the movement from point A to point C is called as change in demand. As far as the shift in market demand is concerned, all those factors that results in shift in demand by individuals is also contributes towards the change in market demand. For example, if there is change in price of the substitutes, we can observe change in demand of the commodity. If price of complement changes in the market, again there is change in demand for the commodity. For example, if we assume milk and cereal are complement of each other, if price of cereal increases then it might be possible there is decrease in demand for milk. Because milk and cereal are complement to each other, so increase in price of one commodity leads decrease in quantity demand for other commodity. And it might be possible that there is change in income in the market, there is change in income by all the individuals in a particular market, may be because of taxation. And because of that imposition of the taxation, when there is decrease in income, when there is decrease in disposable income of the how income of the consumers, then it results in decrease in demand for that particular commodity. And this decrease in the we observe this positive association between income and demand when commodity under consideration is a normal commodity. If price if income increases demand will increase if commodity under consideration is a normal commodity, but if commodity under consideration is an inferior commodity, then in that case increase in income results in decrease in demand for that particular commodity. For example, it might be possible for few individuals, beef is an inferior commodity. If income of the household increases, then it might be possible there is decrease in demand of beef. As far as the interpretation of the market demand is concerned, it is very important for the firms. Basically, for the firm it is essential to have the knowledge about the properties of the market demand. When we say properties of the market demand, a firm should have information about the nature of the market in which they are selling their product, whether the market is a perfectly competitive market or market is an imperfectly competitive market. So the nature of the market has some influence about the decision making of the firms. And information about the presence of substitute or complement also play its role in the decision making by the firms. Similarly, when we say firm makes their production schedules based on the demand for their product in the market, when we say demand for their product in the market, it might be possible demand for a particular product in the market is elastic in nature or in elastic in nature. When we say demand for a product is elastic, it basically indicate that the small change in price brings about significant change in quantity demand. So firms are very much concerned about the nature of the elasticity of the commodity that they are selling in the market. And at the same time, market demand is very important for policy makers because this is the information that they use for the formulation of the policy, for the formulation of the policies about the products that are being sell in the market. For example, it might be possible if market if quantity under consideration is a necessity item, then policy makers will try to keep the prices of that particular commodity in the market relatively low as compared to other items in the market. So in this module, we are basically discussed about the demand by individuals, willingness and ability to buy by a particular individual. Then by aggregating demand by all the individuals in the market, we reported market demand and then we make a differentiation between change in quantity demand and change in demand. Thank you very much.