Définition
The population pyramid represents the breakdown of the population by gender and age at a given point in time. It consists of two histograms, one for each gender (by convention, men on the left and women on the right) where the numbers are shown horizontally and the ages vertically. The numbers by gender and by age depend on interactions between fertility, mortality and migrations. The shape of the pyramid and its variations over the years depend above all on the variations in fertility.