The Holy See can be considered to be the government of the Roman Catholic Church. The term is a bit complicated, however, and it can be used to refer to a number of different entities. Ot includes the territory of Vatican City; the literal seat or cathedra of the Pope in the Basilica of St. John Lateran in Rome; the Pope himself, who is sovereign over the Vatican City territory; and the other bodies of the government, known collectively as the Roman Curia.
In former centuries, the Holy See held sovereignty over a much larger territory in Italy known as the Papal States. In the mid-19th century, Italian nationalists began encroaching on the Papal States, and the territory was finally eliminated altogether in 1870. Vatican City was established in 1929 through the Lateran Treaty, an agreement between the Holy See and the Italian government. Named after the Roman Curia, sometimes called the Vatican, Vatican City was created as a tangible symbol of the independence of the Church as a political and diplomatic entity.
This government is complex, with three Tribunals, nine Congregations, 11 Pontifical Councils, and many offices with various functions. Second in importance to the pope is the Secretariat of State, whose incumbent, the Cardinal Secretary of State — officially called Secretary of State of His Holiness The Pope — is similar to the prime minister in many secular governments. From 2006 to early 2013, the holder of this office was Tarcisio Cardinal Bertone, but he left office when Pope Benedict XVI resigned. In addition to the management of worldwide Church affairs and doctrine, the Holy See has offices dealing with judicial and financial functions.
The Holy See has a rich history of diplomatic relations dating from the 4th century. Today, it boasts 175 diplomatic relationships around the world, spanning every continent, along with 179 permanent diplomatic missions. Since its establishment in the 15th century, the Secretariat of State has overseen these relations. The government is also an active member of many international organizations, and an observer in many more, including the United Nations.