A curia is an official body that governs a particular Church in Roman Catholicism. These curias range from the relatively simple diocesan curia, to the larger patriarchal curias, to the Roman Curia, which is the central government of the Catholic Church. Other Roman Catholic bodies, such as religious institutes, may also have curias. For example, the Legion of Mary has a rank called the Curia. It stands above the Praesidium but below the Regia. The Curia is responsible for several Praesidia.
These curias are historically descended from the Roman Curiae, and they keep that name even though they now have very different functions. When the Roman Empire collapsed, many of the administrative functions previously done by the state were subsumed by the only solid institution left, which was the church. The Bishop and curia took the place of the government officials, often to the point of sitting at the same chair in the same building. The Curia therefore passed into religious hands, and afterwards changed functions many times but always keeping its traditional name, at least in those Christian denominations that keep a strong continuity with the Apostolic tradition.
Every diocese and eparchy has a curia, consisting of the chief officials of the diocese. These officials assist the diocesan bishop in governing the particular church.
This diocesan curia includes the vicar general, who is normally also the moderator of the curia, any episcopal vicars, the chancellor of the curia, vice-chancellors and notaries, and a finance officer and financial council. The bishop may also add other officials of his choice.