What do population pyramids primarily illustrate?

Population pyramids primarily illustrate age structure within a population. They are graphical representations that show the distribution of various age groups in a population, which is often divided by gender. The shape of the pyramid can indicate growth trends, declining populations, or stability within a society. A wide base typically signifies a high birth rate, while a narrow base can indicate lower birth rates and an aging population. By analyzing the age structure, researchers can infer potential issues related to demographics, such as the economic implications of an aging population or the need for services geared towards youth. This information is vital for planning in healthcare, education, and labor markets, making age structure a fundamental aspect of population studies.