The United Nations was officially established in 1945 after World War II.
The UN Charter was signed by representatives of 50 countries in San Francisco on 26 June 1945. It entered into force on 24 October 1945, the date now celebrated annually as United Nations Day. Poland signed later, bringing the number of original member states to 51.
The organization was created to help prevent another global war, support international cooperation and provide a forum for diplomacy. Its name had already been used during World War II by the Allied powers, and the UN succeeded the League of Nations, which had been established after World War I.
The UN’s main organs include the General Assembly, Security Council, International Court of Justice, Secretariat, Economic and Social Council and Trusteeship Council. The organization is not a world government: its powers depend on its charter, member states and, in many cases, Security Council decisions.
The founding year is sometimes confused with 1944, when planning conferences helped shape the organization, or 1946, when the General Assembly first met in London.