The Feast of the Annunciation, contemporarily the Solemnity of the Annunciation, also known as Lady Day, the Feast of the Incarnation (Festum Incarnationis), Conceptio Christi (Christ’s Conception), commemorates the visit of the archangel Gabriel to the Virgin Mary, during which he informed her that she would be the mother of Jesus Christ, the Son of God. It is celebrated on 25 March each year. In the Roman Catholic Church, when 25 March falls during the Paschal Triduum, it is transferred forward to the first suitable day during Eastertide. In Eastern Orthodoxy and Eastern Catholicism, it is never transferred, even if it falls on Pascha (Kyriopascha.
The Feast of the Annunciation is observed almost universally throughout Christianity, especially within Orthodoxy, Anglicanism, Catholicism, and Lutheranism. It is a major Marian feast, classified as a solemnity in the Catholic Church, a Festival in the Lutheran Churches, and a Principal Feast in the Anglican Communion. In Orthodox Christianity, because it announces the incarnation of Christ, it is counted as one of the 8 great feasts of the Lord, and not among the 4 great Marian feasts, although some prominent aspects of its liturgical observance are Marian. Two examples in liturgical Christianity of the importance attached to the Annunciation are the Angelus prayer, and especially in Roman Catholicism, the event's position as the first Joyful Mystery of the Dominican Rosary.