The population age structure is is simply the structure of a population in a given time period by age groups. In order to represent the population age structure in a simple and efficient way, the population pyramid is used. Depending of what type of population is dominant, the pyramid will have different shapes. It can easily show us the trends and type of demographic transition for a particular population. When there high birthrates, the pyramid tends to be widest at the bottom, but when there's low birthrates the pyramid tends to be widening in the middle and upper sections.
