Cold War terminology was developed during the Cold War era. Familiar and still used by many, it classifies countries into first world, second world, and third world nations based on their respective economic development and standards of living. When this nomenclature was developed, capitalistic democracies such as the United States and Japan were considered part of the first world. The poorest, most undeveloped countries were referred to as the third world and included most of sub-Saharan Africa, Latin America, and Asia. The second world was the in-between category: nations not as limited in development as the third world, but not as well off as the first world, having moderate economies and standard of living, such as China or Cuba. Later, sociologist Manual Castells (1998) added the term fourth world to refer to stigmatized minority groups that were denied a political voice all over the globe (indigenous minority populations, prisoners, and the homeless, for example).
Also during the Cold War, global inequality was described in terms of economic development. Along with developing and developed nations, the terms less-developed nation and underdeveloped nation were used. This was the era when the idea of noblesse oblige (first-world responsibility) took root, suggesting that the so- termed developed nations should provide foreign aid to the less-developed and underdeveloped nations in order to raise their standard of living.