Life Expectancy: Life expectancy is the average number of years an individual is expected to live based on current mortality rates. Increasing longevity often leads to higher life expectancies within populations.
Ageing Index: The ageing index measures the ratio between older individuals (typically aged 65 and above) and younger individuals (usually below 15) within a population. A higher ageing index indicates a larger proportion of elderly people compared to young ones.
Gerontology: Gerontology is the study of aging processes, including physical changes, psychological aspects, social implications, and societal responses related to growing older populations. It encompasses various disciplines such as biology, psychology, sociology, etc., that focus on understanding aging phenomena.