A concordat is a convention between the Holy See and a sovereign state that defines the relationship between the Catholic Church and the state in matters that concern both, i.e. the recognition and privileges of the Catholic Church in a particular country and with secular matters that affect church interests.

The Holy See, also called the See of Rome, Petrine See or Apostolic See, is the jurisdiction of the pope in his role as the Bishop of Rome. It includes the apostolic episcopal see of the Diocese of Rome, which has ecclesiastical jurisdiction over the worldwide Catholic Church and sovereignty over the city-state known as the Vatican City. As the supreme body of government of the Catholic Church, the Holy See enjoys the status of a sovereign juridical entity under international law.