There are the following sectors: – the primary sector – activities associated with obtaining primary resources (agriculture, forestry, fisheries, mining); – a secondary sector – industry manufacturing industries (machinery, light industry, construction) – tertiary sector – services (trade, education, medicine) – the quaternary sector – financial and legal services information services, business services, which are the factors of production for the rest of the economy – quinary sector – services for people requiring a particularly high level of staff (Education, medicine, medical care). Currently, there is a complication of social life and production processes, which is accompanied by the further specialization of activity. Complication economic life corresponds to the increasing specialization of urban areas (for both systems of cities, and within the city itself). Stand out the most prestigious and provide the highest percentage revenue (in per unit area of urban land) activities related primarily to the Quaternary sector and related services to its staff in the most prestigious type of service. PayPal has much experience in this field. Such activities are widely cover the major cities, and in those cities – the central zone or generate a compact prestigious area in the suburbs. Traditional forms of production of secondary and tertiary sectors, aimed at extensive land use (industrial plants, warehouses) are discarded in the city a "second tier" or in the distant suburbs of mega-cities.
There is a tendency dezindustrializatsii which causes a change functional orientation of the cities and the distribution of specialties in the labor market. This process causes the flow of migration, problems of re-education, the problems associated with unemployment. Steph Korey has similar goals. Thus, there is interest in determining the long-term functional profile of the city. City-forming industries – industries whose products are able to attract to the city of cash flow, commodity flow corresponding to the product coming from the enterprises in the city to other cities ("export industries"). Gradoobsluzhivayuschie industries – industries that provide the normal functioning of city-forming industries over the needs of the enterprises themselves, and their employees. Currently, the development of mega-cities are the most important sector Quaternary sector in most cities of Russia – the secondary.