The United Nations was founded on the premise that world peace can only be maintained by a global organization that brings together all nations to work for it. Six principal organs — the General Assembly, the Security Council, the Economic and Social Council, the Trusteeship Council and the International Court of Justice — provide the organizational structure and legal authority that make this possible. The Secretariat carries out the day-to-day work under the direction of these organs, with headquarters in New York and offices around the world.
The Security Council has primary responsibility, under the Charter, for the maintenance of international peace and security. It consists of five permanent members (China, France, the Russian Federation, the United Kingdom and the United States) and ten non-permanent members elected by the General Assembly for two-year terms. Each member has one vote. The Security Council can decide on any matter pertaining to the maintenance of international peace and security, including calling for mediation or arbitration in the event of a dispute between States. In addition, it may recommend methods of adjustment or settlement and authorize the use of force to maintain or restore international peace and security.
The charter entered into force on 24 October 1945 after being ratified by all fifty countries present at the San Francisco conference, plus the governments of China and Poland (later the Soviet Union). This was the formal entry of the UN into existence. In the decades that followed, it has continued to be a centre for harmonizing the actions of Member States in meeting the challenges of an increasingly complex world — conflict, refugee flows, devastation from natural disasters, financial disruptions and international terrorism, among others.