The rosary is one of those stereotypical Catholic things: if someone is a Catholic on TV, chances are that at some point, either a rosary or a medal will be pulled out to indicate the person's Catholicism. Sometimes you see them dangling from rearview mirrors (which makes me cringe). There's really no doubt that the rosary is a Big Thing in Catholicism.
But what the heck is it?
The rosary is a series of prayers. The rosary itself--the physical object--is what's called a chaplet, because there's not a bead for every decade (known as a 15 or 20 decade rosary). The "normal" rosary you see is a five decade chaplet. Many religious orders wear the complete rosary as part of their habit.
The rosary is made up of four main prayers: The Our Father, The Hail Mary, the Apostles' Creed, and the Glory Be. The bulk of the rosary is Hail Marys. There are 20 decades--sets of 10 beads--divided into four categories, arranged around the life of Jesus. These are the "mysteries of the rosary."
The mysteries are: (with Biblical citations in parentheses; I haven't listed all the appropriate scriptures, in some cases)
The Joyful Mysteries
1. The Annunciation: The Angel Gabriel appears to Mary and she agrees to be the Mother of the Savior (Lk. 1: 26-8)
2. The Visitation: Mary visits her cousin Elizabeth, who is pregnant with St. John the Baptist. (Lk 1: 39-56)
3. The Nativity: Jesus is born in Bethlehem (Lk. 2:1-20)
4. The Presentation in the Temple: Mary and Jesus dedicate Jesus at the Temple in Jerusalem. (Lk. 2:22-38)
5. Finding the Child Jesus: Joseph and Mary find Jesus, after three days of being lost, in the Temple, teaching to the elders, scribes, etc. . (Lk 2: 41-51)
The Luminous Mysteries (introduced by St. John Paul II in 2002)
1. The Baptism in the Jordan: John baptizes Jesus (Mk 1:9-11)
2. The Wedding Feast at Cana: Jesus turns water into wine--his first miracle (Jn 2: 1-11)
3. The Preaching of the Kingdom: This mystery contains all of Jesus' public works: preaching, miracles, etc. (Mt, Mk, Lk, Jn)
4. The Transfiguration: Jesus' divinity is revealed before three of his Apostles, along with visions of Elijah and Moses. (Mt 17:1-9)
5. The Institution of the Holy Eucharist: Jesus gives the apostles His Body and Blood at the Last Supper, under the appearance of bread and wine. (Lk. 22:14-20, Mt. 26: 26-29, Mk 14: 22-25)
The Sorrowful Mysteries
1. The Agony in the Garden: Jesus prays in the Garden of Gethsemane before His arrest. (Mk. 32-42)
2. The Scourging at the Pillar: Jesus is beaten by the Roman soldiers (Jn. 19:1)
3. The Crowning of Thorns: Jesus is mocked by the Roman soldiers; a crown of thorns is made and pushed onto His head. (Jn 19:2)
4. The Carrying of the Cross: Jesus carries His cross through the streets of Jerusalem to Golgotha (Mt 27:32-34; Mk 15:20-33; Lk 23:26-31; Jn 19: 16-18
5. The Crucifixion: Jesus is crucified and dies. (Mk 15:33-40; Lk 23:32-56, Jn 19: 19-42)
The Glorious Mysteries
1. The Resurrection: Jesus rises from the dead (Mt 28: 1-10; Mk 16:1-8; Lk 24: 1-12; Jn 20:1-23)
2. The Ascension: Jesus bodily returns to His Father in Heaven (Mt. 28:16-20; Lk 24:50-53; Acts 1:1-11)
3. The Descent of the Holy Spirit: The Holy Spirit comes upon the Apostles on Pentecost (Acts 2: 1-43)
4. The Assumption: Mary is assumed, body and soul, into Heaven
5. Mary is Crowned Queen of Heaven: Mary enters into Heaven and receives the rewards of the Just.
Did you notice a few things about this? Even though the "Hail Mary" is what's said on the 10 beads of each decade, most of these mysteries are Christocentric--meaning, Christ is at the center of them. Yes, we're using the Hail Mary, but we're meditating on the mysteries in the life of Christ and His mother. Every mystery that appear "Mary-centric" always involves Jesus! And almost all of the mysteries are Biblically based, taken directly from the Gospels, as are the prayers; the "Our Father" is the prayer that Jesus taught us, and the Hail Mary is from the Gospel of Luke.
OK, so how do you pray it?
First, you select a set of mysteries to pray (this assumes you're not going to go through all 20--you can do that, though!). If it's a Monday, Wednesday, or Saturday, it's traditionally the Joyful Mysteries. Tuesdays and Fridays, Sorrowful. Wednesday and Sunday, Glorious. Thursday, Luminous. But you can pick whatever you want. Then, meditating on one mystery per decade, you just pray it.
It can sound repetitive and boring. But it really isn't. Each mystery brings you deeper into the lives of Mary and Jesus, and even the apostles, in some of them. This is Christian meditation at its best. The Hail Mary provides a sort of "background music" to your meditation. Many times I've gotten to the end of a decade and been surprised! (The "Our Father" beads are usually bigger than the rest of the beads, so you have a tactile reminder that the decade's over.) And sometimes I don't go that deeply into meditation. I'm tired, I'm sick, whatever. I just pray, and think about the mysteries, or the person I'm praying for. When I say I'm praying for you, it usually means you're getting a decade of my daily rosary.
The rosary is a powerful, powerful prayer. (note about that link: don't go clicking around on that site if you're not already a solid Catholic. It's....weird. But this list is legit.) It's stopped wars . (This link explains why we celebrate Our Lady of the Rosary on October 7!) It's, by far, my favorite way to pray. It's completely portable--you don't even need beads, you can use your fingers. It's extremely calming.
The rosary is actually one of the things that led me to know my Dominican vocation. The Dominicans invented the rosary. Well, OK, not invented. Mary gave it to St. Dominic. So he didn't invent it. But they have such a strong dedication to the rosary! That's why it's part of the Dominican habit. It's worn where a sword used to be worn--indicating its powerful status!
Now, that being said, it's not a vending machine. It's not a chain letter: pray the rosary and GET WHATEVER YOU DESIRE! No. Not gonna work like that. But it is an immensely powerful prayer, and one that I would love to encourage you to try.
There are few prayers better than the rosary. Give it a try!