Economic sector

One classical breakdown of economic activity distinguishes three sectors:

In the 20th century, economists began to suggest that traditional tertiary services could be further distinguished from "quaternary" and quinary service sectors.

An economy may include several sectors (also called "industries") that evolved in successive phases:

Even in modern times, developing countries tend to rely more on the first two sectors, in contrast to developed countries.

An economy can also be divided along different lines:

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