The population structure for an area shows the number of males and females within different age groups in the population. This information is displayed as an age-sex or population pyramid. Population pyramids of LEDCs (Less Economically Developed Countries) typically have a wide base and a narrow top. This represents a high birth rate and high death rate. Population pyramids of MEDCs (More Economically Developed Countries) typically have a roughly equal distribution of population throughout the age groups. The top obviously gets narrower as a result of deaths. Population pyramids for every country in the world can be found here. Population pyramids are used to show the structure of the population according to age and sex. Click here to see the three major types of population pyramid.
The video below provides a really good explanation of population pyramids and discusses how the world’s demography is changing