The distribution of the population according to different types of occupations is referred to as the occupational structure.An enormous variety of.occupations are found in any country. These occupations can be classified into three categories: primary, secondary and tertiary.
(i) Primary activities include agriculture, animal husbandry, building and construction work, etc.
(ii) Secondary activities include manufacturing industry, building and construction work, etc.
(iii) Tertiary activities include transport, communications, commerce, administration and other services.