The prayer of the Virgin Mary
That is why the Canticle of Mary, The Magnificat (Latin) or Megalynei (byzantine) is the song both of the Mother of God and of the Church; the song of the Daughter of Zion and of the new People of God; the song of thanksgiving for the fullness of graces poured out in the economy of salvation and the song of the "poor" whose hope is met by the fulfillment of the promises made to our ancestors, "to Abraham and to his posterity for ever."
Source: Catechism of the Catholic Church (Vatican.va)