[Micro economics is known as Price theory]: The subject matter of micro economics includes the theory of product and factor pricing. The theory of product pricing explains how the prices of different commodities such as cloth, wheat, rice, sugar, etc. are determined. The theory of factor pricing explains how prices of various factors of production such as rent for land, wages for labour, interest for capital and profits for entrepreneur are determined. These are determined by the forces of demand and supply in the economy. Micro economics helps in determining product prices as well as factor prices.
Therefore, Micro economics is not known as income theory but is known as price theory.