What does 'natural increase' in population refer to?

Natural increase in population specifically refers to the phenomenon where the number of births in a certain area surpasses the number of deaths over a given period. This calculation does not take into consideration migration; instead, it focuses solely on the vital statistics of births and deaths. Essentially, a society experiences natural increase when the birth rate is higher than the mortality rate, leading to a rise in the population count.

This concept is fundamental in understanding demographic changes and trends within a population, as it represents organic growth. It is crucial for policymakers and planners as they forecast future population dynamics and needs related to healthcare, education, and infrastructure. Other options do not reflect this definition, as they introduce elements like immigration, death rates without context of births, or economic factors, which do not pertain to natural population growth as defined by births exceeding deaths.