Life expectancy is a demographic measure that refers to the average number of years that a person can expect to live based on current mortality rates. It is often used as an indicator of the overall health and well-being of a population. Factors that can influence life expectancy include access to healthcare, lifestyle choices, socioeconomic status, and environmental factors. Studying life expectancy can help researchers understand trends in population health, develop public health policies, and plan for the future healthcare needs of a population.