A papal legate – from the Latin, authentic Roman title Legatus – is a personal representative of the pope to foreign nations, or to some part of the Catholic Church. He is empowered on matters of Catholic Faith and for the settlement of ecclesiastical matters.
The legate is appointed directly by the pope (the bishop of Rome and head of the Catholic Church). Hence a legate is usually sent to a government, a sovereign or to a large body of believers (such as a national church) or to take charge of a major religious effort, such as an ecumenical council, a crusade to the Holy Land, or even against a heresy such as the Cathars.
The term legation is applied both to a legate's mandate and to the territory concerned (such as a state, or an ecclesiastical province). The relevant adjective is legatine.
There are several ranks of papal legates, some of which no longer exist today:
Read more about Papal Legate: Apostolic Nuncio, Apostolic Delegate, Legatus A Latere, Legatus Natus, Legatus Missus, Gubernatorial Legates, History