The United Nations (UN) is an intergovernmental organization established 24 October 1945 to promote international co-operation. A replacement for the ineffective League of Nations, the organization was created following the Second World War to prevent another such conflict. At its founding, the UN had 51 member states; there are now 193. The headquarters of the United Nations is in Manhattan, New York City, and enjoys extraterritoriality. Further main offices are situated in Geneva, Nairobi and Vienna. The organization is financed by assessed and voluntary contributions from its member states. Its objectives include maintaining international peace and security, promoting human rights, fostering social and economic development, protecting the environment, and providing humanitarian aid in cases of famine, natural disaster, and armed conflict.
In the century prior to the UN's creation, several international treaty organizations and conferences had been formed to regulate conflicts between nations, such as the International Committee of the Red Cross and the Hague Conventions of 1899 and 1907.Following the catastrophic loss of life in the First World War, the Paris Peace Conference established the League of Nations to maintain harmony between countries. This organization resolved some territorial disputes and created international structures for areas such as postal mail, aviation, and opium control, some of which would later be absorbed into the UN. However, the League lacked representation for colonial peoples (then half the world's population) and significant participation from several major powers, including the US, USSR, Germany, and Japan; it failed to act against the Japanese invasion of Manchuria in 1931, the Second Italo-Ethiopian War in 1935, the Japanese invasion of China in 1937, and German expansions under Adolf Hitler that culminated in the Second World War.
The United Nations was formulated and negotiated among the delegations from the Soviet Union, the UK, the US and China in Dumbarton Oaks Conference.[14][15] After months of planning, the UN Conference on International Organization opened in San Francisco, 25 April 1945, attended by 50 governments and a number of non-governmental organizations involved in drafting the United Nations Charter. The UN officially came into existence 24 October 1945, upon ratification of the Charter by the five permanent members of the Security Council—France, the Republic of China, the Soviet Union, the UK and the US—and by a majority of the other 46 signatories.