Some industry sectors include oil, farming, car manufacturing, health care and banking. The industries are broken up into four major groups according to their place in the economic chain. The four categories are primary, secondary, tertiary and quaternary.
Primary industries are involved in the extraction of raw material or natural resources from the earth or sea. Aside from oil and farming, such sectors include fishing, mining and forestry. Secondary industries take these natural resources and make them into products through manual labor or the use of machines. All sectors in the manufacturing industry are in this category. Tertiary industries offer services to other people and industries. Aside from the health care industry, sectors in this industry include those in hospitality and entertainment.
At one point, these were the three major categories of industries. Analysts added a fourth category to include sectors in the high-tech industry, which formerly belonged to the tertiary category. Research development companies are the most common in this category, but it includes any sector with a primary purpose in the technological field. All of the industry sectors are linked economically, given that a large number of natural resources are extracted, manufactured into goods, delivered through the service industry to customers, and researched or developed using high-tech equipment.