Net migration: the difference between immigration and emigration for a particular country.Emigration: the migration of people from a country to one or a number of other countries.Immigration: the migration of people into a country from one or a number of other countries.Natural decrease: when the numbers of births is lower than the number of deaths.
Census: an official periodic count of a population including such information as age, gender, occupation and ethnic origin.Rate of natural change: the difference between the birth rate and the death rate.Crude death rate: the number of deaths per 1000 population in a given year.It is only a very broad indicator as it does not take into account the age and gender distribution of the population. Crude birth rate: the number of births per 1000 population in a given year.Demographic transition: the historical shift of birth and death rates from high to low levels in a populations.this situation is due to past high fertility rates which result in large numbers of young people.