The document summarizes the main sectors of the Indian economy - primary, secondary, and tertiary - and classifies them based on the nature of economic activities. The primary sector involves extraction and production of natural resources like agriculture and mining. The secondary sector is related to manufacturing activities like steel production. The tertiary sector provides services to society such as transportation, banking, and insurance. The three sectors are interdependent. The document also discusses classification of the economy based on ownership into public and private sectors, and based on employment into organized and unorganized sectors.