Solemnity
The feast of the Annunciation marks the visit of the angel Gabriel to the Virgin Mary, during which he told her that she would be the mother of Jesus Christ, the Son of God. It is celebrated on 25 March each year.
More importantly, since it occurs 9 months before the birth of Jesus on Christmas Day, the Annunciation marks the actual incarnation of Jesus Christ - the moment that Jesus was conceived and that the Son of God became the son of the Virgin.
The feast has been celebrated since the 5th century AD and celebrates two things:
God's action in entering the human world as Jesus in order to save humanity
Humanity's willing acceptance of God's action in Mary's freely given acceptance of the task of being the Mother of God
In the first reading from the prophet Isaiah (7:10-14; 8:10) we hear the prophecy of the coming of Emmanuel “The Lord himself, therefore will give you a sign. It is this: the maiden is with child and will soon give birth to a son whom she will call Emmanuel, a name which means “God-is-with-us”. The second reading from the letter to the Hebrews (10:5-10) reminds us that Christ came to do the Father’s will and that will “was for us to be made holy by the offering of the body made once and for all by Jesus Christ.” In the Gospel from Luke (1:26-38) we hear the story of the Annunciation and Mary’s words “I am the handmaid of the Lord, let what you have said be done to me.”