The Archbishop of Canterbury is the chief bishop and principal leader of the Church of England, the symbolic head of the worldwide Anglican Communion, and the diocesan bishop of the Diocese of Canterbury. In his role as head of the Anglican Communion, the archbishop leads the third largest group of Christians in the world.
In the Middle Ages there was considerable variation in the methods of nomination of the Archbishop of Canterbury and other bishops. At various times the choice was made by the canons of Canterbury Cathedral, the King of England, or the Pope. Since the English Reformation, the Church of England has been more explicitly a state church and the choice is legally that of the British crown; today it is made in the name of the Sovereign by the Prime Minister, from a shortlist of two selected by an ad hoc committee called the Crown Nominations Commission.