Mary was the mother of Jesus. Catholics have always had a special devotion to Mary (CCC 971). This special devotion, a devotion that is greater than the honor or veneration given to any other saint, is directed to Mary for many reasons–she alone among all humans was given the "fullness of grace" (Luke 1:28); she was the most blessed of all women (Luke 1:28, 42, 48); she had the honor of being the mother of God (Luke 1:43), by giving birth to Jesus, who was God made man; and she was perfectly obedient to God and cooperated with His will (CCC 148). Mary said "yes" to God when His angel, Gabriel, told her she would bear the Son of God: "I am the handmaid of the Lord. May it be done to me according to your word" (Luke 1:38); she heard the word of God and kept it (Luke 11:27-28). Mary was unique among all humans for many reasons.
Mary was the mother of God. Since Jesus is God, and Mary is the mother of Jesus, then Mary is the mother of God (CCC 495). Besides being the mother of Jesus in the flesh, Mary is also the mother of all believers in spirit: "Then the dragon became angry with the woman [Mary] and went off to wage war against the rest of her offspring, those who keep God's commandments and bear witness to Jesus [Christians]" (Rev. 12:17). Since Mary is the mother of Christ, and the body of Christ is the Church, Mary is the mother of the Church, or of all believers (CCC 963). According to the last mystery of the rosary, Mary is also the "Queen of Heaven and Earth" (CCC 966): "A great sign appeared in the sky, a woman clothed with the sun, with the moon under her feet, and on her head a crown of twelve stars" (Rev. 12:1). Mary is Queen by the fact that she is the mother of the "King of Kings" (Rev. 17:14), Jesus Christ. This is a fulfillment of the Old Testament, where the mother of the king ruled alongside the king as the "queen mother" (1 Kgs. 2:19; 1 Kgs. 15:9-13; 2 Kgs. 10:13-14, 11:1-3; 2 Chron 22:2-4).
By a miracle of God, Mary conceived Jesus while she was still a virgin: "the virgin shall be with child, and bear a son" (Is. 7:14; CCC 498). This is called the "virgin birth". However, even after the birth of Jesus, Mary remained a virgin (CCC 510). It was important that Mary and Joseph devoted their lives to raising the Son of God, so they abstained from intercourse, and Mary had no other children (CCC 494). This is what is called the "perpetual virginity" of Mary. (Those referred to as the "brothers" of Jesus in the Bible were actually his cousins; the word "brother" was often used then to refer to relatives such as cousins, uncles, and nephews).
Mary was also conceived without original sin (CCC 491). All humans inherit original sin the moment they are conceived: "I was born guilty, a sinner, even as my mother conceived me" (Ps. 51:7). Mary was the Ark of the New Covenant (CCC 2676) by the fact that she carried God the Son in her womb (The Ark of the Covenant in the Old Testament was a container that held among other things the tablets given to Moses–it was where the glory of God dwelled). Since it would have been unfitting for Jesus to be carried in the womb of an unregenerated or sinful woman, God applied to Mary ahead of time the grace that Jesus would obtain for mankind by His sacrificial death, so that she would not be stained with original sin. Because of the grace of God, Mary also remained sinless throughout her life (CCC 411; 508). One of the penalties of original sin was death and the corruption (decay) of the body in the grave (CCC 405). Because Mary was preserved from original and actual sin, she received the privilege of being assumed body and soul into heaven on the completion of her earthly life (CCC 966). These beliefs about Mary are called "The Immaculate Conception" and "The Assumption".
Mary is also given the titles of "Co-Redemptrix", "Mediatrix", and "Advocate". Mary is co-redemptrix because she offered up Jesus' sacrificial death on the cross, in union with her maternal sufferings, for the redemption of mankind (CCC 494; 968). Christ's sacrificial death redeemed mankind, and according to the will of God, Mary participated in that redemption, so that Jesus redeemed mankind in union with His mother Mary. This is prophesied by Simeon, when he says: "And you yourself shall be pierced with a sword–so that the thoughts of many hearts might remain bare" (Luke 2:35). Mary is mediatrix because no grace is given to anyone without Mary's intercession (CCC 969). Mary interceded with Christ when he performed his first miracle by turning water into wine (John 2:1-11), which is symbolic of the fact that Mary is the Mediatrix. It is said that Mary dispenses God's grace according to the will of God. Mary is advocate because she offers all prayers and intentions to God the Father through Jesus Christ. Key to understanding these teachings is the concept of Mary as the "New Eve"–Jesus is the Second Adam, who gives life rather than the death that entered the world through Adam (Rom. 5:12-19), so Mary is the Second Eve, symbolically referred to by Jesus as the "Woman" (John 2:4, 19:26), who would battle with the snake [Satan], as God had said (Gen. 3:15), and would participate in Jesus' saving work, just as Eve had participated in Adam's act of disobedience (CCC 411).
Christians have honored Mary through various devotions–the rosary, the scapular, prayers to Mary, songs about her, the veneration of her images, etc. But one of the greatest devotions to Mary is the Consecration to Jesus through Mary. This consecration consists in believers giving all they are and all they do to Jesus through the intercession of Mary, who always has the best interests of the believer at heart, and who knows how to best distribute the grace obtained by prayers and penances. According to the method of St. Louis de Montfort, one prepares for 33 days, with prayers and devotions, before consecrating himself to Jesus through Mary.
Mary has been God's messenger, especially in latter days. Many people have reported Marian apparitions, or appearances and visions of Mary. In 1858, in Lourdes, France, the Virgin Mary appeared 18 times to Bernadette Soubirous, a 14-year old girl. During one apparition, water came up out of the ground to form a spring. People were soon reporting that the waters were miraculous. A blind man regained his sight after washing his eyes in the spring. A dying baby fully recovered after her mother dipped him in. A woman with her face half-eaten away had it miraculously restored. Millions visit each year, and thousands have reported cures. In 1917, in Fatima, Portugal, the Virgin Mary appeared to three children on 6 occasions. During the final apparition, the sun spun around like a fiery wheel, casting out beams of light. It then got larger, terrifying the people, before returning. Mary told the children that if people lived the messages she gave, there would be peace. If not, she said, the world would be the victim of a worse war (World War II), Russia would spread her errors (communism) throughout the world, and there would be an assassination attempt made on the pope. These prophecies were all fulfilled. Mary asked that Russia, for the sake of its conversion, be consecrated to her, which was done by the Pope in 1984 (and soon thereafter resulted in Russia's conversion). Mary also asked for the First Saturdays Devotion be practiced by all Catholics, consisting of receiving communion, going to confession, meditating on the mysteries of the rosary for 15 minutes, and saying five decades of the rosary, all on the first Saturday of five consecutive months, all with the intention of making reparation to sins against the Immaculate Heart of Mary. The infamous "Third Secret of Fatima", which predicted the attempted assassination of the Pope, was fulfilled in 1981, when John Paul II was wounded by a bullet. According to some, Mary began appearing to six teenagers in 1981, and revealed 10 secrets, concerning future events, which can be averted through conversion, prayer, penance, faith, fasting, and peace.