The United Nations (UN) is an intergovernmental organization established on 24 October 1945 t o promote international co-operation. A replacement for the ineffective League of Nations,(国际联盟) the organization was created following the Second World War to prevent another such conflict. At its founding, the UN had 51 member states; there are now 193. The UN Headquarters （总部）is situated in Manhattan, New York City and enjoys extraterritoriality. Further main offices are situated in Geneva, Nairobi and Vienna. The organization is financed by assessed and voluntary contributions from its member states. Its objectives include maintaining international peace and security, promoting human rights, fostering social and economic development, protecting the environment, and providing humanitarian aid in cases of famine, natural disaster, and armed conflict.1.On 25 April 1945, the UN Conference on International Organization began in San Francisco, attended by 50 governments and a number of non-governmental organizations involved in drafting the United Nations Charter. The UN officially came into existence on 24 October 1945 upon ratification of the Charter by the five then-permanent members of the Security Council—France, the Republic of China, the Soviet Union, the UK and the US—and by a majority of the other 46 signatories.The first meetings of the General Assembly, with 51 nations represented, and the Security Council took place in Methodist Central Hall Westminster in London beginning 6 January 1946. The General Assembly selected New York City as the site for United Nations Headquarters, and the facility was completed in 1952. Its site—like UN headquarters buildings in Geneva, Vienna, and Nairobi—is designated as international territory.The Norwegian Foreign Minister, Trygve Lie, was elected as the first UN Secretary-General.1945年4月25日，联合国国际组织会议在旧金山召开，50国政府及诸多非政府机构参与并起草了《联合国宪章》。
1945年10月24日，当时的安理会五大常任理事国（法国、中华民国、苏联、英国和美国）及多数其他签署国（46国）共同批准了宪章，联合国正式宣告成立。
1946年1月6日，联合国大会第一次会议（51个国家代表出席）以及安理会在英国伦敦的卫理公会中央礼堂举行。
大会选定纽约作为联合国总部，其设施于1952年完工。
联合国总部同联合国在日内瓦、维也纳和内罗毕的总部一样，被指定为国际领土。
同时，大会还选举了挪威外相特吕格韦·赖伊为第一任联合国秘书长。
2.The United Nations' system is based on five principal organs: the General Assembly, the Security Council, the Economic and Social Council (ECOSOC), the Secretariat, and the International Court of Justice.[42] A sixth principal organ, the Trusteeship Council, suspended operations in 1994, upon the independence of Palau, the last remaining UN trustee territory.2.1The General Assembly is the main deliberative assembly of the United Nations. Composed of all United Nations member states, the assembly meets in regular yearly sessions, but emergency sessions can also be called.The assembly is led by a president, elected from among the member states on a rotating regional basis, and 21 vice-presidents.The first session was convened on 10 January 1946 in the Methodist Central Hall Westminster in London and included representatives of 51 nations.When the General Assembly votes on important questions, a two-thirds majority of those present and voting is required. Examples of important questions include recommendations on peace and security; election of members to organs; admission, suspension, and expulsion of members; and budgetary matters. All other questions are decided by a majority vote. Each member country has one vote. Apart from approval of budgetary matters, resolutions are notbinding on the members. The Assembly may make recommendations on any matters within the scope of the UN, except matters of peace and security that are under consideration by the Security Council.联合国大会是联合国的主要合议性团体，包括联合国的所有会员国，每年定期举行会议，但紧急会议亦可以召开[54]。
大会由一位主席（由成员国中产生，根据区域进行轮换）和21位副主席主持[55]。
第一次会议于1946年1月10日在伦敦西敏卫理公会中央礼堂召开，有51个国家的代表参会[10]。
大会对于重要问题的投票需要到场且投票的三分之二多数才能通过。
重要问题的例子包括关于和平和安全的建议、主要机构的选举、接纳、暂停和开除会员，以及预算事宜[56]。
其他问题则由简单多数决定。
每个国家只有一票。
除预算事项外，通过的决议对于会员没有约束力。
大会可以对联合国范围内的一切事项提出建议，但关于和平和安全的事项则属安全理事会考量2.2The Security Council is charged with maintaining peace and security among countries. While other organs of the United Nations can only make "recommendations" to member states, the Security Council has the power to make binding decisions that member states have agreed to carry out, under the terms of Charter Article 25.The decisions of the Council are known as United Nations Security Council resolutions.The Security Council is made up of 15 member states, consisting of 5 permanent members—China, France, Russia, the United Kingdom, and the United States—and 10 non-permanent members—Argentina (term ends 2014), Australia (2014), Chad (2015), Chile (2015), Jordan (2015), Lithuania (2015), Luxembourg (2014), Nigeria (2015), Republic of Korea (2014), and Rwanda (2014).[59] The five permanent members hold veto power over UN resolutions, allowing a permanent member to block adoption of a resolution, though not debate. The ten temporary seats are held for two-year terms, with member states voted in by the General Assembly on a regional basis.[60] The presidency of the Security Council rotates alphabetically each month.安全理事会的职责是维护国家之间的和平与安全。