The UN Charter is the treaty that forms and establishes the international organization called the United Nations.  The Charter of the United Nations was signed on June 26, 1945 in San Francisco at the conclusion of the United Nations Conference on International Organization.  It was signed by 50 of the 51 original member countries.  It entered into force on October 24, 1945, after being ratified by the five permanent members of the Security Council—the Republic of China, France, the USSR, the United Kingdom, and the United States—and a majority of the other signatories.

Most countries in the world have now ratified the Charter.

The Charter consists of a preamble and a series of articles grouped into chapters.  The Preamble of UN Charter states:

“We the peoples of the United Nations determined: to save succeeding generations from the scourge of war, which twice in our lifetime has brought untold sorrow to mankind, and to reaffirm faith in fundamental human rights, in the dignity and worth of the human person, in the equal rights of men and women and of nations large and small, and 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, And for these ends: to practice tolerance and live together in peace with one another as good neighbors, and to unite our strength to maintain international peace and security, and to ensure, by the acceptance of principles and the institution of methods, that armed force shall not be used, save in the common interest, and to employ international machinery for the promotion of the economic and social advancement of all peoples, Have resolved to combine our efforts to accomplish these aims: Accordingly, our respective Governments, through representatives assembled in the city of San Francisco, who have exhibited their full powers found to be in good and due form, have agreed to the present Charter of the United Nations and do hereby establish an international organization to be known as the United Nations.”

• Chapter I: Purposes and Principles including the important provisions of the maintenance of international peace and security.
• Chapter II: Membership
• Chapter III: Organs
• Chapter IV: The General Assembly
• Chapter V: The Security Council
• Chapter VI: Pacific Settlement of Disputes
• Chapter VII: Action with Respect to Threats to the Peace, Breaches of the Peace and Acts of Agression
• Chapter VIII: Regional Arrangements
• Chapter IX: International Economic and Social Co-operation
• Chapter X: The Economic and Social Council
• Chapter XI: Declaration regarding Non-Self-Governing Territories
• Chapter XII: International Trusteeship System
• Chapter XIII: The Trusteeship System
• Chapter XIV: The International Court of Justice
• Chapter XV: The Secretariat
• Chapter XVI: Miscellaneous Provisions
• Chapter XVII: Transitional Security Arrangements
• Chapter XVIII: Amendments
• Chapter XIX: Ratification and Signature

Amendments to Articles 23, 27 and 61 of the Charter were adopted by the General Assembly on December 17, 1963 and came into force on August 31, 1965. A further amendment to Article 61 was adopted by the General Assembly on December 20, 1971, and came into force on September 24, 1973. An amendment to Article 109, adopted by the General Assembly on December 20, 1965, came into force on June 12, 1968.

The amendment to Article 23 enlarges the membership of the Security Council from eleven to fifteen. The amended Article 27 provides that decisions of the Security Council on procedural matters shall be made by an affirmative vote of nine members and on all other matters by an affirmative vote of nine members, including the concurring votes of the five permanent members of the Security Council.

The amendment to Article 61, which entered into force on August 31, 1965, enlarged the membership of the Economic and Social Council from eighteen to twenty-seven. The subsequent amendment to that Article, which entered into force on September 24, 1973, further increased the membership of the Council from twenty-seven to fifty-four.

The amendment to Article 109, which relates to the first paragraph of that Article, provides that a General Conference of Member States for the purpose of reviewing the Charter may be held at a date and place to be fixed by a two-thirds vote of the members of the General Assembly and by a vote of any nine members of the Security Council. Paragraph 3 of Article 109, which deals with the consideration of a possible review conference during the tenth regular session of the General Assembly, has been retained in its original form in its reference to a “vote, of any seven members of the Security Council”, the paragraph having been acted upon in 1955 by the General Assembly, at its tenth regular session, and by the Security Council.