United Nations System
There are 15 members of the Security Council, consisting of five veto-wielding permanent members (China, France, Russia, the United Kingdom, and the United States) and 10 elected non-permanent members with two-year terms. This basic structure is set out in Chapter V of the UN Charter. Security Council members must always be present at UN headquarters in New York so that the Security Council can meet at any time.
Aftermath of World War II
The five major Allied powers were given permanent membership in the United Nations Security Council. The permanent members can veto any United Nations Security Council resolution, the only UN decisions that are binding according to international law. The five powers at the time of founding were: the United States of America, the United Kingdom, France, the Soviet Union and the Republic of China. The Republic of China lost the Chinese Civil War and retreated to the island of Taiwan by 1950 but continued to be a permanent member of the Council even though the "de facto" state in control of mainland China was the People's Republic of China (PRC). This was changed in 1971 when the PRC was given the permanent membership previously held by the Republic of China. Russia inherited the permanent membership of the Soviet Union in 1991 after the dissolution of that state.