Human Development Index is known as HDI.
It determines the development of a countries population looking through the per capita income, health, education and many other social factors.
Through the HDI a countries social health in large and economic health, in general, is reflected. The real development is reflected through this index.
When a country has a high HDI, it essentially means that the lifespan is higher, the education levels are higher along with higher per capita income. This makes the country a developed country. Countries like USA, France Japan have high HDIs’ making them developed countries.