According to About.com, primary occupations are those that extract or harvest products from the Earth, secondary occupations involve the manufacturing of finished goods, and tertiary occupations are those in the service industry. These sectors categorize occupations on a continuum of distance from the Earth's natural environment.
Jobs in the primary sector are associated with the production of basic foods and raw materials. The primary sector encompasses agriculture, farming, forestry, grazing, hunting, mining, quarrying, fishing, hunting and gathering.
The secondary sector of the economy includes manufacturing and construction. Occupations in the secondary sector include automobile production, metal working and smelting, engineering, energy utilities, textile production, chemical industries, breweries and bottlers, shipbuilding and aerospace manufacturing.
Jobs in the tertiary sector offer services to businesses and the general population. Occupations associated with the tertiary sector include retail and wholesale, restaurants, media and entertainment, transportation, clerical services, law, healthcare, banking, insurance and tourism.
About.com explains that the economy’s quaternary sector encompasses intellectual activities, such as government, culture, education, scientific research, information technology and libraries. Lastly, the quinary sector involves the highest level of decision making in an economy or society, and it includes the top officials or executives in various fields.
The BBC states that a nation’s employment structure reveals how the labor force is divided into different sectors. There is a unique employment structure in every country. Most of the rich countries generally have more people that work in the tertiary or quaternary sector.