The Angelus is a Prayer based on the Gospel of Luke1:28 in the Bible. The Angel Gabriel greeted Mary with the following:
28 And the angel being come in, said unto her: Hail, full of grace, the Lord is with thee: blessed art thou among women.
26 And in the sixth month, the angel Gabriel was sent from God into a city of Galilee, called Nazareth, 27 To a virgin espoused to a man whose name was Joseph, of the house of David; and the virgin's name was Mary. 28 And the angel being come in, said unto her: Hail, full of grace, the Lord is with thee: blessed art thou among women. 29 Who having heard, was troubled at his saying, and thought with herself what manner of salutation this should be. 30 And the angel said to her: Fear not, Mary, for thou hast found grace with God.
31 Behold thou shalt conceive in thy womb, and shalt bring forth a son; and thou shalt call his name Jesus.
The Angelus (Latin for Angel) is a Christian devotion in memory of the Incarnation. The name Angelus is derived from the opening words: Angelus Domini nuntiavit Mariæ and is practiced by reciting as versicle and response three Biblical verses describing the mystery; alternating with the salutation "Hail Mary!". The devotion was traditionally recited in Catholic churches, convents, and monasteries three times daily: 6:00 am, noon, and 6:00 pm (many churches still follow the devotion and some practice it at home). The devotion is also used by some Anglican and Lutheran churches. The Angelus is usually accompanied by the ringing of the Angelus bell, which is to spread good-will to everyone on Earth.
reference : http://en.wikipedia.org/wiki/Angelus