The Security Council was established by the UN Charter. Its primary responsibility is to work to maintain international peace and security. The presidency of the Council is held by each of the members in turn for one month, following the English alphabetical order of the Member States names. The president of the United Nations Security Council is the presiding officer of that body. The president is the head of the delegation from the United Nations Security Council member state that holds the rotating presidency. The council has 15 members elected for two-year terms.