In religion, a curia consists of a group of officials who assist in the governance of a particular Church. 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 bodies, such as religious orders, 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 Praesidium.
All of these have now very different functions from the Curia in Roman times, but they keep the name since they are historically descended from it. In other words, when the Roman Empire collapsed, many of the administrative functions previously done by the state where subsumed by the only solid institution left, which was the church. The Bishop and its clergy basically took the place of the officials that the government used to send, to the point of actually sitting at the same chair in the same building. So the Curia passed in religious hands, and afterwards changed functions many times but always keeping its traditional name, at least in those Christian denominations that still keep a strong continuity with the Apostolic tradition.
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.
The patriarchal curia consists of the permanent synod of the Church, the chancellor, assistant chancellor, and notaries, the patriarchal finance officer, the patriarchal liturgical commission and other patriarchal commissions, and the patriarchal tribunal. Up to three bishops may be elected specifically to serve in the patriarchal curia.