The place where the Pope lives is referred to in many ways, the least clear of which is the Holy See. Most people use this term as if they understand what it means. They probably should, and so should you, but as long as there is a slight possibility you do not, here is what you should know.
In the Catholic Church, a Bishop has ecclesiastical jurisdiction over a geographical territory known as an episcopal see or more commonly as a diocese. The word “see” derives from the Latin word sedes or “seat” and refers metaphorically to a Bishop’s chair, or cathedra, which was an early symbol of a Bishop’s authority.
An Apostolic See is a see created by one of the original Apostles. As the sole remaining Apostolic See, St. Peter’s Roman See became the Apostolic See and then the Holy See (Latin: sancta sedes). It is also the seat of the Bishop of Rome, who by definition is the Pope. Therefore, the Holy See is the ecclesiastical “seat of government” of the entire Catholic Church.
Although the church’s headquarters are often informally referred to simply as “the Vatican”, the Holy See and the State of the Vatican City are not the same thing. Vatican City is an enclave located entirely within the city of Rome. The smallest independent state in the world, it was created in 1929 with the Lateran Treaty between the Holy See and Italy, which assigned full sovereignty to the Holy See. Therefore Vatican City is a country but not a sovereign state. Foreign ambassadors are assigned to the Holy See and not Vatican City, and likewise Papal representatives represent the Holy See abroad. In terms of government, Vatican City is a theocracy and an absolute monarchy administered by the elected Pope and the Roman Curia.