The distribution of the population according to the different types of occupations is referred to as the occupational structure. Occupations are generally classified as primary (agriculture, mining, fishing, etc.), secondary (manufacturing industry, building and construction work, etc.) and tertiary (transport, communications, banking, etc.).
The proportion of people working in different activities reflects the economic development of a country. Developed nations have a high proportion of people in secondary and tertiary activities. Developing countries tend to have a higher proportion of their workforce engaged in primary activities.