United Nations Day marks the anniversary of the entry into force of the UN Charter in 1945. With the ratification of this founding document by the majority of its signatories, including the five permanent members of the Security Council, the United Nations officially came into being. The date of 24 October has been celebrated as United Nations Day since 1948.

After World War I, it was decided that a treaty was needed to prevent another world war, so the Treaty of Versailles was created. This treaty was essentially supposed to be a League of Nations to prevent further outbreaks of war, to encourage diplomatic solutions and negotiations between countries. However, the League of Nations failed to prevent World War II, so it was decided that a different approach was needed to keep the world from repeatedly plunging into war.

Developed toward the end of World War II, the idea of the United Nations emerged as a solution to the myriad of problems that beleaguered the earlier League of Nations. United Nations Day is intended to help people remember the four main purposes of the United Nations: (1) to maintain peace and security all over the world, (2) to develop relationships among member nations, (3) foster an atmosphere of communication between nations, and (4) provide a forum to bring countries together to meet the purposes and goals of the U.N. The Council is composed of 15 Members, including five permanent members (China, France, Russian Federation, the United Kingdom, and the United States) and ten non-permanent members that are elected for two-year terms by the General Assembly.