The Gini index (or coefficient) is a synthetic indicator that captures the level of inequality for a given variable and population. It varies between 0 (perfect equality) and 1 (extreme inequality). Between 0 and 1, the higher the Gini index, the greater the inequality.
It is equal to 0 in a situation of perfect equality where the variable takes an identical value over the whole population. At the other extreme, it is equal to 1 in the most unequal situation possible, where the variable is equal to 0 over the entire population except for one individual .
Inequality measured in this way can relate to variables such as income, wages, standard of living, etc.