(a) Change in taste or fashion.
(b) Change in income.
(c) Change in other prices.
(d) Discovery of substitutes.
(e) Ancipatory changes in prices also affect the law of demand.
(f) When a commodity is such that its use confers distinction.

Price is the value of the good expressed in terms of money. Price of a good is fixed by the forces of demand for and supply of the good. Price determines what goods are to be produced and in what quantities. It also decides how the goods are to be produced.

According to Benham, "A study of the factors affecting the size, distribution and stability of a country's national income".

Consumer's Equilibrium refers to a situation under which a consumer spends his entire income on purchase of a goods in such a manner that it gives him maximum satisfaction and he has no tendency to change it.

(i) In ordinary language desire and want mean the same thing.
(ii) But in economics, they have different meanings. Wants are the basis for human behaviour to buy and consume goods.

Important external economies of scale are
(i) Increased transport facilities
(ii) Banking facilities
(iii) Development of townships.
(iv) Development of information and communication.

The various types of Internal Economies of scale are
(a) Technical Economies
(b) Financial Economies
(c) Managerial Economies
(d) Labour Economies
(e) Marketing Economies
(f) Economies of survival

Degrees of price elasticity of Demand :
(i) Perfectly elastic demand
(ii) Perfectly inelastic demand
(iii) Unitary elastic demand
(iv) Relatively elastic demand
(v) Relatively inelastic demand

According to Engel's Law "The proportion of total expenditure incurred on food items declines as total expenditure [which is proxy for income] goes on increasing."

(i) Real income is the amount of goods that can be purchased with money as income.
(ii) It is the purchasing power of income which is based on the rate of inflation.

"The study of how men and society choose, with or without the use of money, to employ scarce productive resources which could have alternative uses, to produce various commodities over time, and distribute them for consumption, now and in the future among various people and groups of society." - by Paul Samuelson.

Environmental economics which analyses the inter relationship between economy and environment. It is a study of inter disciplinary tools for the problems of ecology, economy and environment.

The amount of Money, which the firm receives by the sale of its output in the market is known as its revenue.

Income represents the amount of monetary (or) other returns either earned (or) unearned small or big accruing over a period of time to an economic unit.

Lionel Robbins defines "Economics is a science which studies human behaviour as a relationship between ends and scarce means which have alternative uses".

Price line (or) Budget line is represented by set of indifference curve depends on his money income and price level.

Determinants of Elasticity of demand
i) Availability of substitutes.
ii) Proportion of Consumer's Income.
iii) Number of uses of Commodity.
iv) Complementarity between goods and
v) Time.

a. Production Function: The functional relationship between inputs and outputs is known as production function Inputs refers to the factors services which are used in production i.e. Land labour capital and enterprise Output refers to the volume of goods produced
b. Classification of production function: Production function may classified into two:
i. Short-run production function which is studied through Law of Variable Proportions.
ii. Long-run production function which is explained by Returns to scale.

Division of labour means dividing the process of production into distinct and several component processes and assigning each component in the hands of a labour or a set of labourers who are specialists in the particular process the concept of Division of Labour was introduced by Adam Smith.

Locus of different combination of two commodities.

(a) Monopoly - Single
(b) Duepoly - Two seller
(c) Oligopoly - A few sellers

(i) An Iso quant curve can be defined as the locus of points representing various combinations of two inputs capital and labour yielding the same output.
(ii) The Iso quant is also called as the "Equal product curve" (or) The "Iso-Product curve".

Market demand means the total quantity of a commodity that all its buyers are willing to purchase at different prices over a given period of time.

Indifference map refers to a set of indifference curves corresponding to different income levels of satisfaction.