United Nations Security Council
Along with the five permanent members, the Security Council of the United Nations has temporary members that hold their seats on a rotating basis by geographic region. Non-permanent members may be involved in global security briefings. In its first two decades, the Security Council had six non-permanent members, the first of which were Australia, Brazil, Egypt, Mexico, the Netherlands, and Poland. In 1965, the number of non-permanent members was expanded to ten.
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."