September 12, 2021 is the annual United Nations Day for South-South Cooperation. Until 2011 this date took place on December, 19, but it had been removed to the date of the acceptance of the "Buenos Aires Plan of Action for Promoting and Implementing Technical Cooperation among Developing Countries" in 1978. South-South Cooperation names the exchange of resources, technology and knowledge between the developing nations.
These nations are countries which hold a rather low status of economic, social and political development. They are commonly considered as “poor”. Which countries fall in that category depends on the standard one would use. So the United Nations Day for South-South Cooperation celebrates annually the political relationships between developing countries.