Basically UN system is composed of six principle organs, viz.
1. General Assembly – The General Assembly is the main deliberative, policymaking and representative organ of the United Nations. Comprising all 193 Members of the United Nations, it provides a unique forum for multilateral discussion of the full spectrum of international issues covered by the Charter. The Assembly meets in regular session intensively from September to December each year, and thereafter as required. Each country has one vote. Some Member States in arrear of payment may be granted the right to vote. The GA has established a number of Councils, Working Groups, Boards, etc. for the performance of its functions.
2. Security Council – The UN Charter established six main organs of the United Nations, including the Security Council. It gives primary responsibility for maintaining international peace and security to the Security Council, which may meet whenever peace is threatened. All members of the United Nations agree to accept and carry out the decisions of the Security Council. While other organs of the United Nations make recommendations to member states, only the Security Council has the power to make decisions that member states are then obligated to implement under the Charter. The Security Council is composed of five permanent members and 10 non-permanent members.
4. The Secretariat — an international staff working in duty stations around the world — carries out the diverse day-to-day work of the Organization. It services the other principal organs of the United Nations and administers the programmes and policies laid down by them. At its head is the Secretary General, who is appointed by the General Assembly on the recommendation of the Security Council for a five-year, renewable term.
The duties carried out by the Secretariat are as varied as the problems dealt with by the United Nations. These range from administering peacekeeping operations to mediating international disputes, from surveying economic and social trends and problems to preparing studies on human rights and sustainable development. Secretariat staff also inform the world’s communications media about the work of the United Nations; organize international conferences on issues of worldwide concern; and interpret speeches and translate documents into the Organization’s official languages.
5. International Court of Justice – The International Court of Justice (ICJ) is the principal judicial organ of the United Nations (UN). It was established in June 1945 by the Charter of the United Nations and began work in April 1946.
The seat of the Court is at the Peace Palace in The Hague (Netherlands). Of the six principal organs of the United Nations, it is the only one not located in New York (United States of America).
The Court’s role is to settle, in accordance with international law, legal disputes submitted to it by States and to give advisory opinions on legal questions referred to it by authorized United Nations organs and specialized agencies.
The Court is composed of 15 judges, who are elected for terms of office of nine years by the United Nations General Assembly and the Security Council. It is assisted by a Registry, its administrative organ. Its official languages are English and French.
6. Trusteeship Council – The Trusteeship Council suspended operation on 1 November 1994, with the independence of Palau, the last remaining United Nations trust territory, on 1 October 1994. By a resolution adopted on 25 May 1994, the Council amended its rules of procedure to drop the obligation to meet annually and agreed to meet as occasion required — by its decision or the decision of its President, or at the request of a majority of its members or the General Assembly or the Security Council. Under the Charter, the Trusteeship Council is authorized to examine and discuss reports from the Administering Authority on the political, economic, social and educational advancement of the peoples of Trust Territories and, in consultation with the Administering Authority, to examine petitions from and undertake periodic and other special missions to Trust Territories.
The following is a list of affiliates of the above mentioned organs of United Nations System .