Permanent members of the United Nations Security Council
The permanent members of the United Nations Security Council (also known as the Permanent Five, Big Five, or P5) are the five states which the UN Charter of 1945 grants a permanent seat on the UN Security Council: China (formerly the Republic of China), France, Russia (formerly the Soviet Union), the United Kingdom, and the United States. These countries were all allies in World War II, which they won. They are also all nuclear weapons states. A total of 15 UN member states serve on the UNSC, the remainder of which are elected. Any one of the five permanent members have the power of veto, which enables them to prevent the adoption of any "substantive" draft Council resolution, regardless of its level of international support.
Chapter V of the United Nations Charter
Article 23 establishes the composition of the Security Council, with five permanent members (the Republic of China, ("currently" People's Republic of China), France, the Soviet Union, the United Kingdom, and the United States) and 10 non-permanent members elected by the General Assembly. The non-permanent members serve two year terms and cannot be immediately re-elected. In the selection process for these non-permanent members, the treaty calls for "due regard being specially paid, in the first instance to the contribution of Members of the United Nations to the maintenance of international peace and security and to the other purposes of the Organization, and also to equitable geographical distribution."