A population pyramid, also known as an age-sex pyramid, is a graphical representation that illustrates the distribution of a population by age groups and sex.

Key features and functions:

• Structure: It typically consists of two back-to-back bar graphs, with the population's age groups displayed on the vertical axis and the number or percentage of males and females in each age group on the horizontal axis.
• Shape: The shape of a population pyramid provides insights into a population's demographic history and future trends. For example:
  • A broad base indicates a high birth rate.
  • A narrow top suggests a low life expectancy.
  • Irregularities can reflect past events such as wars, famines, or epidemics.
• Analysis: Population pyramids are used by demographers, sociologists, and policymakers to analyze population trends, make projections, and plan for future needs in areas such as healthcare, education, and employment.

For a more detailed explanation and examples, you can refer to resources like the Population Reference Bureau: What is a Population Pyramid?