The primary sector of the economy involves changing natural resources into primary products. Most products from this sector are considered raw materials for other industries. Major businesses in this sector include agriculture, agribusiness, fishing, forestry and all mining and quarrying industries.
The secondary sector of the economy includes those economic sectors that create a finished, usable product:manufacturing and construction.
This sector generally takes the output of the primary sector and manufactures finished goods or where they are suitable for use by other businesses, for export, or sale to domestic consumers. This sector is often divided into light industry and heavy industry. Many of these industries consume large quantities of energy and require factories and machinery to convert the raw materials into goods and products. They also produce waste materials and waste heat that may pose environmental problems or cause pollution.
The tertiary sector of economy (also known as the service sector or the service industry) is one of the three economic sectors, the others being the secondary sector (approximately manufacturing) and the primary sector (extraction such as mining, agriculture and fishing). Sometimes an additional sector, the "quaternary sector", is defined for the sharing of information (which normally belongs to the tertiary sector).
The quaternary sector of the economy is an extension of the three-sector hypothesis of industrial evolution. It principally concerns the intellectual services: information generation, information sharing, consultation, education and research and development. It is sometimes incorporated into the tertiary sector but many argue that intellectual services are distinct enough to warrant a separate sector.
This sector evolves in wel developed countries and requires a highly educated workforce.[