The Human Development Index (HDI) is a composite statistic of life expectancy, education, and per capita income indicators, which are used to rank countries into four tiers of human development. It was introduced by the United Nations Development Programme in 1990 to provide a broader measure of development beyond just economic growth. HDI aims to reflect the overall well-being of a country's citizens, emphasizing the importance of health and education in addition to economic factors. Countries with higher HDI scores are generally considered to have better living standards and quality of life for their populations.