In economics, underdevelopment is when resources are not used to their full socio-economic potential, with the result that local or regional development is slower in most cases than it should be. Furthermore, it results from the complex interplay of internal and external factors that allow less developed countries only a lop-sided development progression. Underdeveloped nations are characterized by a wide disparity between their rich and poor populations, and an unhealthy balance of trade. Symptoms of underdevelopment include lack of access to job opportunities, health care, drinkable water, food, education and housing.