Expanding population pyramids have a wide base and a narrow top, indicating a high birth rate and a low death rate. This is typically seen in developing countries, where the majority of the population is young and there is a high potential for population growth.

Stationary population pyramids have a uniform shape and indicate that the birth rate and death rate are in balance, which means that population growth is stable. This is often seen in developed countries where fertility rates are low and the population is aging.

Contracting population pyramids have a narrow base and a wide top, indicating a low birth rate and a high death rate. This is usually seen in developed countries with aging populations.

The limits of population pyramids can be seen in countries where the pyramid is contracting and a large proportion of the population is older. These countries are facing significant challenges such as increased healthcare costs, pension challenges and labor shortage, which can affect the economy. The aging population also challenges the social welfare system and the ability of the society to care for the elderly.

Additionally, population pyramids can also be affected by migration and changes in the population structure. These shifts can change the demographic trends, affecting the economy and society in different ways, and countries need to adapt to these changes in order to ensure a sustainable and prosperous future.