The Human Development Index (HDI) is a composite statistic (composite index) of life expectancy, education, and per capita income indicators, which are used to rank countries into four tiers of human development. A country scores higher HDI when the lifespan is higher, the education level is higher, and the GDP per capita is higher. The HDI was developed by Pakistani economist, Mahbub ul Haq, for the UNDP.
The 2010 Human Development Report introduced an Inequality-adjusted Human Development Index (IHDI). While the simple HDI remains useful, it stated that "the IHDI is the actual level of human development (accounting for inequality)", and "the HDI can be viewed as an index of 'potential' human development (or the maximum IHDI that could be achieved if there were no inequality)".
The index is based on the human development approach, developed by Ul Haq, often framed in terms of whether people are able to "be" and "do" desirable things in life. Examples include—Beings: well fed, sheltered, healthy; Doings: work, education, voting, participating in community life. It must also be noted that the freedom of choice is central—someone choosing to be hungry (e.g. during a religious fast) is quite different to someone who is hungry because they cannot afford to buy food.