The document discusses various definitions and perspectives on the concept of underdevelopment. It notes that while difficult to define, underdeveloped countries generally share some common characteristics including lower levels of living and productivity, lower levels of human capital, higher levels of inequality and poverty, high population growth rates, greater social fractionalization, larger rural populations undergoing rapid urbanization, and lower levels of industrialization and manufactured exports. The document explores these characteristics in further detail and provides country-level examples and statistics to illustrate differences between developed and underdeveloped economies.