Economic sectors

The economy includes several sectors (also called industries), that evolved in successive phases.
The ancient economy was mainly based on subsistence farming.
The industrial revolution lessened the role of subsistence farming, converting it to more extensive and monocultural forms of agriculture in the last three centuries. The economic growth took place mostly in mining, construction and manufacturing industries.
In the economies of modern consumer societies there is a growing part played by services, finance, and technology -- the (knowledge economy).
In modern economies, there are three main sectors of economic activity:
Primary sector: Involves the extraction and production of raw materials, such as corn, coal, wood and iron. (A coal miner and a fisherman would be workers in the primary sector.)
Secondary sector: Involves the transformation of raw or intermediate materials into goods e.g. manufacturing steel into cars, or textiles into clothing. (A builder and a dressmaker would be workers in the secondary sector.)
Tertiary sector: Involves the provision of services to consumers and businesses, such as baby-sitting, cinema and banking. (A shopkeeper and an accountant would be workers in the tertiary sector.)
More details about the various phases of economic development follow. As this process was far from being homogenous geographically, the balance between these sectors differs widely among the various regions of the world.

The range of activities involved

The fields of study exploring, registering and describing the economy or a part of it, belong in general to the social sciences and include economics as well as branches of history (economic history) or geography (economic geography).
Practical fields directly related to the human activities involving production, distribution, exchange, and consumption of goods and services as a whole, range from engineering to management and business administration to applied science to finance.
All kind of professions, occupations, economic agents or economic activities, contribute to the economy.
Consumption, saving and investment are core variable components in the economy and determine market equilibrium.
There are three main sectors of economic activity: primary, secondary and tertia