His Holiness The Pope: The origin of this title is fairly self-explanatory. Since St. Peter was elected pope by God Himself, it seems plausible that Peter and the successive popes would be particularly blessed by God's patronage.
Bishop Of Rome And Vicar Of Jesus Christ: In ancient times Rome was the center of the world and its culture. Thus, historically, it is and was appropriate that the pope who is the head of the Church, should be head also of this city.
Successor Of St. Peter, Prince Of The Apostles: Each pope stands in the place of St. Peter, who was the Prince of the Apostles, and each pope receives Peter's authority through the fourth mark of the Church: apostolic succession. The responsibility of shepherding all Catholics is placed upon the pope.
Supreme Pontiff Of The Universal Church: "Pontiff" means a "bridge builder." The Pope builds bridges between God and Man and between Man and Man.
Patriarch Of The West; When the Roman Empire split in two, the highest authority in the east came to be known as a patriarch. The head of Rome is naturally the head of the west and as the highest authority, receives the title "Patriarch."
Servant Of The Servants Of God: Christ said "If I then, your Lord and Teacher, have washed your feet, you also ought to wash one another's feet." The pope and all priest fulfill the injunction placed on him by Christ to become servants - however, as the pope is the Prince of the Apostles, he is likewise the Servant of the Servants.
Primate Of Italy: A Primate is a bishop of highest rank in a province or country, so the pope is the primate of Italy and all the world.
Archbishop And Metropolitan Of The Roman Province: Metropolitan and Archbishop are almost synonymous. This title could be used to call greater attention to the awesome powers invested in the visible head of the Church.
Sovereign Of Vatican City State: since 1929, there has been a small country in the middle of Rome, ruled over by the Pope. It is called the Vatican City State. Its official language is Latin, that probably being the language most familiar to clergy of different countries.