HDI stands for Human Development Index, which is a composite statistic used to measure the overall achievement in a country in three basic dimensions of human development: a long and healthy life, being knowledgeable, and having a decent standard of living.

The concept of HDI was developed by Amartya Sen and Mahbub ul Haq, two economists who worked at the United Nations Development Programme (UNDP).

The HDI was first introduced in 1990 in the Human Development Report published by the UNDP.

The three dimensions of HDI are: 1. A long and healthy life, measured by life expectancy at birth. 2. Being knowledgeable, measured by the mean years of schooling for adults aged 25 and above and expected years of schooling for children of school-entering age. 3. Having a decent standard of living, measured by gross national income (GNI) per capita.

The Gender inequality index (GII) is not a component of the HDI. It is a separate measure that is used to assess gender inequality in a country.

The HDI is calculated by taking the geometric mean of the three dimensions. The geometric mean is used because it gives more weight to lower values, which is important for measuring human development.

The HDI has a range of 0 to 1, where 0 represents the lowest level of human development and 1 represents the highest level of human development.

Norway has the highest HDI in the world, according to the 2020 Human Development Report.

Niger has the lowest HDI in the world, according to the 2020 Human Development Report.

The average HDI of the world is 0.7, according to the 2020 Human Development Report.

The HDI has increased over time. The average HDI in 1990 was 0.595, and it has increased to 0.7 in 2020.

The HDI of a country is affected by a number of factors, including economic growth, government policies, and social and cultural factors.

The HDI has been criticized for being too simplistic, for not taking into account inequality, and for not being a good measure of well-being.

There are a number of alternatives to the HDI, including the Multidimensional Poverty Index (MPI), the Inequality-Adjusted Human Development Index (IHDI), and the Gender Development Index (GDI).

It is not clear what the future of the HDI is. It is possible that it will continue to be used as a measure of human development, that it will be replaced by a new measure, or that it will be used in conjunction with other measures.