A third-world country is an underdeveloped nation with widespread poverty. Most third-world countries are located in Asia, Africa or Latin America. However, the meaning of the term "Third World" has changed since its origin.
The term "Third World" originated after World War II when countries aligned themselves with either the United States or the Soviet Union. Countries that aligned themselves with the United States tended to be developed, capitalist and industrialist nations and were referred to by the term "First World." Countries who aligned themselves with the Soviet Union were called the "Second World"; these included Russia, Eastern European countries and China. "Third World" became the term for all other unaligned countries, mostly in Africa, Asia and Latin America.
Traits found in most third-world countries include a high infant-mortality rate, low economic development, high poverty, underdevelopment of natural resources, dependence on industrialized nations, unstable governments, illiteracy, disease, lack of a middle class and foreign debt. Because many third-world countries share at least some of these traits, the meaning of "Third World" has shifted from "unaligned" to "underdeveloped" nations.
A couple of surprising third-world countries include Saudi Arabia and Greenland. Greenland was underdeveloped for a long time due to Denmark's control, which limited its involvement in international trade. Saudi Arabia was not aligned after World War II, its oil was not discovered until 1938, and it was not developed until 1941. Prior to the development of the oil fields, Saudi Arabia was largely a tribal nation.