Life expectancy is a core demographic metric representing the average number of years a person is predicted to live within a given population, based on current mortality rates and age-specific survival probabilities. It is derived from statistical life tables, which track death rates across different age cohorts within a defined population. The calculation considers factors such as the incidence of age-related illnesses, improvements in medical treatments, and public health standards. Fluctuations in life expectancy reflect changes in the overall health profile of a community, often indicating advances in sanitation, nutrition, or disease management rather than reflecting inherent limits of human biology.