The correct answer is - United Nations.
After the World War II ended, the countries around the world wanted to assure that something so horrible will never happen again to the humanity. Because of this, 51 nations from around the world, gathered and officially formed the organization known as the United Nations.
The purpose of the formation of this organization was the development of nice relations between the nations. The organization to mediate and prevent conflicts around the world. Global economic development, better living standards for everyone in the world, promotion of human rights and social reforms.
In general, the organization has managed to live up to its initial cause, though it has to be mentioned that it has also made some terrible mistakes, or allowed some very inhumane things to happen in certain parts of the world.