# Content The Human Development Index (HDI) is a summary measure of achievements in key dimensions of human development: a long and healthy life, access to knowledge, and a decent standard of living. The HDI is the geometric mean of normalized indices for each of the three dimensions. The health dimension is assessed by life expectancy at birth, the education dimension is measured by mean of years of education for adults aged 25 years and more and expected years of education for children, and the standard of living dimension is measured by gross national income per capita. The Inequality-Adjusted Human Development Index (IHDI) adjusts the HDI for inequality in the distribution of each dimension across the population. The Gender Development Index (GDI) measures gender inequalities in achievement in three basic dimensions of human development: health, measured by female and male life expectancy at birth; education, measured by female and male expected years of education for children and female and male mean years of education for adults ages 25 and older; and command over economic resources, measured by female and male estimated earned income. The Gender Inequality Index (GII) reflects gender-based disadvantage in three dimensions—reproductive health, empowerment, and the labour market—for as many countries as data of reasonable quality allow. It shows the loss in potential human development due to inequality between female and male achievements in these dimensions. The Multidimensional Poverty Index (MPI) identifies multiple deprivations at the household level in education, health, and standard of living as indicators of poverty. It uses micro data from household surveys, and — unlike the IHDI — all the indicators needed to construct the measure must come from the same survey.