Economy is the system of trade and industry by which the wealth of a country is made and used. It is a system which provides the people of society to earn a living.

The market demand for a good at a particular price is the total demand of all consumers taken together.

Average Fixed Cost refers to the fixed cost per unit of output produced. It is derived by dividing the Total Fixed Cost by total quantity of output produced. When the output increases, average fixed cost decreases.

AR curve slope downward in a market in which firm can sell more only by lowering price.

In a perfectly competitive market, firms are price-takers. A price taker firm is the firm which does not has any control over the existing market price and cannot influence it.