How United Nation Came Into existence

The name "United Nations", coined by United States President Franklin D. Roosevelt, was first used in the "Declaration by United Nations" of 1 January 1942, during the Second World War, when representatives of 26 nations pledged their Governments to continue fighting together against the Axis Powers.
States first established international organizations to cooperate on specific matters. The International Telecommunication Union was founded in 1865 as the International Telegraph Union, and the Universal Postal Union was established in 1874. Both are now United Nations specialized agencies.
In 1899, the International Peace Conference was held in The Hague to elaborate instruments for settling crises peacefully, preventing wars and codifying rules of warfare. It adopted the Convention for the Pacific Settlement of International Disputes and established the Permanent Court of Arbitration, which began work in 1902.
The forerunner of the United Nations was the League of Nations, an organization conceived in similar circumstances during the First World War, and established in 1919 under the Treaty of Versailles "to promote international cooperation and to achieve peace and security." The International Labour Organization was also created under the Treaty of Versailles as an affiliated agency of the League. The League of Nations ceased its activities after failing to prevent the Second World War.
In 1945, representatives of 50 countries met in San Francisco at the United Nations Conference on International Organization to draw up the United Nations Charter. Those delegates deliberated on the basis of proposals worked out by the representatives of China, the Soviet Union, the United Kingdom and the United States at Dumbarton Oaks, United States in August-October 1944. The Charter was signed on 26 June 1945 by the representatives of the 50 countries. Poland, which was not represented at the Conference, signed it later and became one of the original 51 Member States.
The United Nations officially came into existence on 24 October 1945, when the Charter had been ratified by China, France, the Soviet Union, the United Kingdom, and the United States and by a majority of other signatories. United Nations Day is celebrated on 24 October each year.

The UN system is often referred to as a "family" of organizations. The charter of the UN, signed in San Francisco on 26 June 1945, defined six main organs of the new world body, each with specific tasks and functions. However, because it was impossible to foresee all the demands that might be made on the organization, provision was made for extending its capacities as the need arose. Thus, three of the main organs are specifically empowered to establish "such subsidiary organs" as may be considered necessary for the performance of their functions. In addition, Article 57 of the charter provides that the various specialized agencies established by intergovernmental agreement and having international responsibilities in economic, social, cultural, educational, health, and related fields "shall be brought into relationship" with the UN. Since the signing of the charter, the UN has established numerous subsidiary organs and has entered into relationship with various independent organizations. Reproduced opposite is a chart showing the various organs and bodies within the UN system.
For assistance in interpreting the chart, a brief survey of the UN's main organs, the different categories of subsidiary organs, and the related agencies is given below. A detailed description of the functioning of each of the main organs and an account of the work of selected subsidiary organs are contained in later chapters of the first section of this volume. The structure and work of the UN specialized and technical agencies are described in the second section.