Monopoly is a market situation in which there is only one seller of a product with barriers to entry of others. The product has no close substitutes. He is a price maker who can set the price to his maximum advantage. This may occur because the firm has a patent on a product or a license from the government to be a monopoly .Pure monopoly occurs when the producer is so powerful that he is always able to take the whole of all consumers' income whatever the level of his output is.