Age structure, population structure, and demographic structure all refer to the distribution of individuals in a population based on their age.

The three main types of age structures are stable, expanding, and contracting.

An expanding age structure is characterized by a high proportion of young individuals and a low proportion of old individuals.

A contracting age structure is characterized by a low proportion of young individuals and a high proportion of old individuals.

A stable age structure is characterized by a relatively equal proportion of individuals in all age groups.

Birth rate, death rate, immigration, and emigration can all affect the age structure of a population.

The age structure of a population can be used to predict the size of the population in the future, the growth rate of the population in the future, and the age distribution of the population in the future.

Age of maturity, age of reproduction, and age of fertility all refer to the age at which an individual reaches sexual maturity.

Age of death, age of mortality, and age of senescence all refer to the age at which an individual dies.

Mean age, median age, and mode age all refer to the average age of individuals in a population.

Reproductive potential, reproductive capacity, and reproductive rate all refer to the proportion of individuals in a population that are in the reproductive age range.

Post-reproductive potential, post-reproductive capacity, and post-reproductive rate all refer to the proportion of individuals in a population that are in the post-reproductive age range.

Pre-reproductive potential, pre-reproductive capacity, and pre-reproductive rate all refer to the proportion of individuals in a population that are in the pre-reproductive age range.

Age-specific fertility rate, age-specific natality rate, and age-specific reproduction rate all refer to the age-specific birth rate.

Age-specific mortality rate, age-specific fatality rate, and age-specific extinction rate all refer to the age-specific death rate.