Primary industries or sectors are concerned with extracting and acquiring raw materials, secondary industries revolve around manufacturing products from raw materials and tertiary industries focus on services that support primary and secondary industries. These sectors form the basis of economies of developed countries. Each step represents the distance away from the natural environment; primary industries extract natural resources while secondary industries turn those resources into products.
Examples of primary sectors of industry including agriculture, mining, oil exploration, forestry, farming, fishing and hunting. Processing and packaging raw materials is also considered a primary sector. Nearly 3 percent of American workers have jobs in primary sectors.
Secondary industries take various raw materials and manufactures them into finished goods. Construction, smelting, automobile manufacturing, textiles, energy utilities, breweries and bakeries are all types of companies involved in secondary economic activity. Assembling large items from parts is also part of secondary industries.
The BBC explains that tertiary industries provide services. Transportation, health care, food service, retail sales, advertising, entertainment, tourism, banking and law are all examples of tertiary-level sectors of the economy. More than 80 percent of Americans are tertiary workers providing services to primary and secondary workers.
Each of these three levels are interdependent on each other. Without raw materials, manufacturers can't make finished goods and workers are unable to sell or transport these manufactured products to customers.