 We are going to study consumer behavior and the topic is normal and the inferior goods. In general life we see that the demand of the commodities expressed by the consumer it varies. We mostly see that if there will be the change in the price, consumer demand will vary. At the same time if the price of good A is going to change it may have an effect on the demand of the commodity B. If we say this in simple words then many times we see that the commodity which the consumer is going to buy because of its own value, the consumer increases or decreases its demand. But many times it happens that instead of its own value, due to the less or greater value of a commodity, its demand changes. But if we see that if we don't differentiate the prices, what difference does the demand of the consumer make by the change of the income? Normally, we say it will be like this that if income will increase, definitely it will increase the purchasing power of the consumer. So, he will have more to purchase, definitely his income increases so his demand will increase. And vice versa is if his income will decrease he has to curtail his purchasing power. Now, what will be the effect of this change in income on all the commodities in the similar manner or the different? When we just measure the change in the quantity demanded with the change in the income, we see that that is one proportion. And that change or the rate of change we express in the form and we say that it is the income elasticity of the demand. Or in other manners we can say it is the responsiveness of a commodity quantity demanded to the responsiveness with the change in the income. Any commodity that increases or decreases its demand, what difference does it make when we measure that difference or change? So, we say that what is the income elasticity? And then we can measure this in the form of percentage. So, with this income or demand analysis, if we see, then we can make four categories of our respective assets. One of which we have Necessary Goods, Number 2, Normal Goods, Number 3, Inferior Goods and 4, the Luxury Goods. Now, if we do an assessment of these four, then we will have Necessary Goods, which consumers have to buy in every way. And there is no difference in the number of income or the number of them. And similarly, Luxury Goods are those Goods that when they have a very sufficient amount of income, they can purchase it. Otherwise, they keep a small portion in their needs. So, next, what we will see in detail, we will discuss two commodities, Normal and Inferior Goods. What is Normal Goods? If we look here, we have drawn different Indifference Curves. And Indifference Curves mostly are present according to the order of preference. And at the same time, consumers have available budget to him that is explained here, where the income is divided by PX and give him the point of X1. And here, the point of X1. Now, we see that the optimal point available to the consumer is point B on this budget line. And there is also one other budget line that is explained this and the consumer is having a optimal choice bundle A. So, consumer is having optimal choice of bundle A when he was having the budget line. Here we can see budget line 1 and he is having the point B when he is having the budget line 2. On the right side movement of the budget line shows that the consumer income has increased. So, with the increase in the income, now consumer is going to have more of the commodity X1 and at the same time, more of the commodity X2. This is the normal behavior in the market. So, any commodity that exhibit this type of the behavior or the properties, we say that that commodity is the normal good. Or if we say in this form that any commodity that increases the demand of the income and reduces the income of the consumer, which normally reduces the demand of the consumer, we call it normal good. And if we see in this form, we say that as the consumer's income increases on the X axis, if we plot it, then the consumer increases the demand for the commodity. And vice versa, if we say that its income will be reduced, then vice versa, its commodity will be reduced. So, this form if we see, we can say that there is a positive relationship between the change in the commodity demanded with the change in the income. Or the income elasticity will always be positive and greater than 0, but it will be less than 1 for the normal good. But it can be equal to 1 only for the other product. Now, coming to the other topic of the inferior goods, we see that there is only one difference. And it is having a contrast than the normal good that with the increase in the income on the vertical axis, consumer is not going to increase the demand, rather it is going to decrease the demand like this. So, here the consumer is having the negative or the inverse relationship. And we can say that the change in the commodity demanded with the change in the income is negative, so its value will be less than 0. So, any commodity that will exhibit this type of the behavior that will be called the inferior good. And when we explain this from the graph, as we have explained in our previous, here there are again various type of the indifference curve. And now the consumer income has increased from this original budget line, say budget line 1 to right side budget line 2. So, with the increase in the income, now we should expect that consumer, it will increase its demand. But consumer has not increased its demand, rather consumer has shift from point A to B. And in this way, the consumer has reduced its consumption of the commodity X2 that is available on the Y axis. In this manner, consumer is treating the commodity at the Y axis as inferior. If we see that this was our expected line, if X2 would not be inferior, so the consumer may have both of X1 and both of X2 in more quantity with the increase in the income. But rather than this, instead of this, if we see that the consumer had shifted to this point, if we see that the commodity of X2 has gone backward, although its income has increased. So, this shift shows, if I join these two points that this type of the curve, it means the backward bending point will be shown by the consumer for the inferior curve.