The Roman Curia is the administrative apparatus of the Holy See and the central governing body of the entire Roman Catholic Church, together with the Pope. It coordinates and provides the necessary central organization for the correct functioning of the Church and the achievement of its goals.
Curia in medieval and later Latin usage means "court" in the sense of "royal court" rather than "court of law". The Roman Curia, then, sometimes anglicized as the Court of Rome, as in the 1534 Act of the English Parliament that forbade appeals to it from England, is the Papal Court, and assists the Pope in carrying out his functions. The Roman Curia can be loosely compared to cabinets in governments of countries with a Western form of governance, but only the Second Section of the Secretariat of State, known also as the Section for Relations with States, and the Congregation for Catholic Education, can be directly compared with specific ministries of a civil government.
The offices in charge of the Vatican City State are not part of the Roman Curia.
While the Pope was sovereign of that region, the Curia had both religious and civil functions. The latter were lost when the Kingdom of Piedmont-Sardinia, expanding to include the greater part of Italy, seized most of the Papal States in 1860 and the city of Rome itself and its surrounding area in 1870, thus ending the Papacy's temporal power. The Curia was from then on dedicated in practice entirely to the Pope's ecclesiastical responsibilities. When the Holy See concluded the Lateran Pacts with the Italian State in 1929, the Holy See recognized the annexation by Italy of the Papal States, and Vatican City State was created. The Curia has continued to devote itself exclusively to ecclesiastical affairs, and a distinct body, not considered part of the Curia, was established for the governance of the minuscule state.
The Second Vatican Council was followed by further changes. Some offices ceased to exist, because their former functions were abolished, as happened with the Dataria. The functions of some others were transferred to another office, as the remaining functions of the Apostolic Chancery and those of the Secretariate of Briefs were transferred to the Secretariat of State, and those of the Congregation of Ceremonies to the Prefecture of the Pontifical Household. Others were split into separate offices, as the Congregation of Rites became the Congregation for the Causes of Saints and the Congregation for Divine Worship, the latter of which later became, by fusion with another office, the Congregation for Divine Worship and the Discipline of the Sacraments. Others again were simply given a new name.
It is normal for every Latin Catholic diocese to have its own curia for its administration. For the Diocese of Rome, these functions are not handled by the Roman Curia, but by the Vicariate General of His Holiness for the City of Rome, as provided by the Apostolic Constitution Ecclesia in Urbe. The Vicar General of Rome, traditionally a Cardinal, and his deputy the Vicegerent, who holds the personal title of Archbishop, supervise the governance of the diocese by reference to the Pope himself, but with no more dependence on the Roman Curia, as such, than other Catholic dioceses throughout the world.
Until a reform by Pope Paul VI in 1969, there still existed hereditary officers of the Roman Curia, holding titles denominating functions that had ceased to be a reality when the Papal States were lost to the papacy.