The Human Development Index (HDI) is a composite statistic of life expectancy, education, and income per capita indicators. A country scores higher HDI when the life expectancy at birth is longer, the education period is longer, and the income per capita is higher. It is used to distinguish whether the country is a developed, a developing or an underdeveloped country. The index was developed in 1990 by Pakistani economist Mahbub ul Haq and Indian economist Amartya Sen. The UN report covers 185 member states of the United Nations (out of 193), along with Hong Kong and Palestine; 8 UN member states are not included because of lack of data. The average HDI of regions of the World and groups of countries are also included for comparison.
Countries fall into four broad human development categories: Very High Human Development, High Human Development, Medium Human Development and Low Human Development.
Because of the new methodology adopted since the 2010 Human Development Report, the new reported HDI figures appear lower than the HDI figures in previous reports.
From 2007 to 2010, the first category was referred to as developed countries, and the last three are all grouped in developing countries. The original "high human development" category has been split into two as above in the report for 2007.
Some older groupings (high/medium/low income countries) that were based on the gross domestic product (GDP) in purchasing power parity (PPP) per capita have been replaced by another index based on the gross national income (GNI) in purchasing power parity per capita.
The only year without a Human Development Report since 1990 was 2012. The latest report was launched on 21 March 2017.