Traditionally, development was defined and measured through economic indicators like GNP per capita. However, modern definitions see development as improving quality of life through meeting basic needs, social justice, health, education, and freedom. Quality of life is now commonly measured through indices like the Physical Quality of Life Index, Human Development Index, and International Human Suffering Index which use a broader range of social and economic factors. However, accurately measuring development remains challenging due to limitations in data collection and inequality within countries.