The purposes, principles, and the organization of the United Nations are outlined in the Charter. The ultimate goals of the United Nations, according to its Charter, are to save succeeding generations from the scourge of war, to reaffirm faith in fundamental human rights, to establish conditions under which justice and respect for the obligations arising from treaties and other sources of international law can be maintained, and to promote social progress and better standards of life in larger freedom. Its primary purpose, therefore, is to maintain international peace and security.
Other important objectives listed in Chapter 1 of the Charter include developing friendly relations among nations based on respect for the principles of equal rights and self-determination of peoples; achieving worldwide cooperation to solve international economic, social, cultural, and humanitarian problems; respecting and promoting human rights; and serving as a centre where nations can coordinate their actions and activities towards these various ends.
Chapter 6 of the Charter provides for the pacific settlement of disputes, through such means as negotiation, mediation, arbitration, and/or judicial decisions. When pacific settlement fails, the goal of collective security whereby the security of each member is assured by all, and aggression against one would be met by the resistance of all underlies the provisions in Chapter 7 for coercive measures, including economic and military sanctions, against an aggressor. In practice, however, collective security has been extremely difficult to achieve. During the Cold War, collective security was replaced by peacekeeping and preventive diplomacy. In the post-Cold War period, appeals to the United Nations for peacemaking purposes increased dramatically, renewing discussion about the feasibility of putting into practice the original UN provisions for collective security.
In addition to traditional peacekeeping and preventive diplomacy tasks, the functions of UN forces in the post-Cold War era have been expanded considerably. From 1990 they supervised elections, encouraged peace negotiation and distributed food in many parts of the world.
(From: The New Encyclopaedia Britannica, V. 2).