(CNN) -- The world will never fully know the unspeakable tortures they endured. But they survived.
Elizabeth Smart was kidnapped from her bedroom at 14, declared a child bride by her captor and sexually assaulted for nine months. Jaycee Dugard, 11, was snatched from a roadside and held for 18 years, eventually bearing two babies fathered by her rapist kidnapper. Taken at 11, Shawn Hornbeck was sexually abused by his abductor for four years before police freed him.
This week in Cleveland, three new names were added to that list of young abduction survivors. After a decade in captivity, Amanda Berry, Georgina "Gina" DeJesus and Michelle Knight now face a challenging journey toward recovery.
What can they learn from the paths followed by Smart, Dugard, Hornbeck and others that led them from darkness to brighter lives?
The resiliency of these survivors is nothing short of remarkable. Smart, now 25, is married. She formed a foundation to battle child abuse and travels the country as a public speaker. Nearly four years after regaining her freedom, Dugard, 33, heads her own group aimed at helping victims like herself. She wrote a book about her ordeal and has learned to ride horseback. Hornbeck, 21, works full-time and wants to finish his education.
Experts credit much of their recovery to access to important health care resources and strong family support.
There's another factor: faith. These survivors likely were more confident that they would re-emerge into a safe world.
"Some of these people have had a considerable amount of faith, and they've entered into a community that has been very accepting and welcoming," said Dr. Wynn Schwartz, a Harvard Medical School psychologist.
Also: time. Smart, Dugard and Hornbeck initially walled themselves off from pesky news reporters, says Dr. Bonny Forrest, a San Diego-based psychologist and attorney. Being "very selective about their interviews allowed them to avoid having to immediately relive and retell" their traumatic experiences. It "allowed them to decompress or let go of their stress in a time period that was appropriate for them."
But for every survivor of childhood abduction, there are countless cases with endings that will never be known.
According to the FBI, more than half of all missing persons cases in the United States involve children.
Specifically, of all 87,217 active missing persons cases in 2012, the FBI says 47,366 missing people were 20 or younger. That's 54.3%. Although many are runaways and don't wish to be found, an unknown number might have been abducted.
For young abductees, experts say, survival is a rare thing.
Here are some of their inspiring stories:
Smart: 'I was marked'
It was late at night inside the bedroom of 14-year-old Elizabeth Smart. A drifter named Brian David Mitchell climbed through a window of her Salt Lake City, Utah, home and put a knife to her throat. He forced her to walk to a nearby campsite, where Mitchell and his wife, Wanda Barzee, "sealed" Smart to him in a brief ceremony and raped her. The couple forced Smart to wander with them from town to town, often keeping her tethered to trees.
Nine months after her abduction, police stopped Mitchell, Barzee and Smart as they left a Walmart in Sandy, Utah, just five miles from her family's home. Smart's life as a captive was finally over.
"I felt that because of what he had done to me, I was marked," Smart later testified at Mitchell's trial. "I wasn't the same. My personal value had dropped. I was nothing. Another person could never love me."
Smart's fears proved to be unfounded as she leaned on her faith and her family. And this past week, she offered to share what she learned during her recovery with the Cleveland victims.
"Nothing that has happened to them will ever diminish their value," Smart told CNN's Wolf Blitzer on Tuesday. "It should never hold them back from doing what they want to do."
Smart reminded them to "take as much time as they need" to recover before going public with the details of their ordeals. "And if they decide never to share their stories, that would be OK, too."
Her remarkable recovery has included co-authoring a Justice Department pamphlet about how to survive abduction. Smart works as a contributor for a national TV news network and she runs a foundation aimed at protecting children from predators.
Last year, Smart married Scotsman Matthew Gilmour, whom she met while they performed missionary work in France for the Church of Jesus Christ of Latter-day Saints.
Dugard focuses on hope
In 1991, Jaycee Dugard was a carefree tween walking toward a school bus stop in South Lake Tahoe, California. But when Phillip and Nancy Garrido drove by looking for a victim, 11-year-old Jaycee's life changed forever.
For the next 18 years, Jaycee became a captive at a hidden compound in Antioch, California. Not allowed to say her own name and raped repeatedly, she bore two daughters fathered by Garrido.
"There's a switch that I had to shut off," she told ABC News' Diane Sawyer. "Just went someplace else." In her book, "A Stolen Life," Dugard wrote that she survived each day by concentrating on her children and the hope of seeing her mother again.
Her captivity ended in 2009 after two police officers at the University of California, Berkeley, met Garrido and the two daughters and noticed "there was just something about the girls that wasn't right." Suspicions after that meeting eventually led to the Garridos' arrest and freedom for Dugard and her little girls.
"You can endure tough situations and survive," she wrote in her book. "Not just survive, but be okay even on the inside, too. I'm not sure how I did endure all that I did. ... I'm beginning to think that I have secretly known all along."
And it was her support network that was key to her recovery. "With the help of my mom and my family, and especially my therapist I have come to realize I can now do things for myself," Dugard wrote. "I can make my own decisions and not worry about if it's not what someone else wants."
Coincidentally, on Tuesday as the Cleveland survivors were tasting their first hours of freedom, Dugard was scheduled to speak at an award ceremony. "What an amazing time to be talking about hope," she told the audience, "with everything that's happening."
Hornbeck: Respect and faith
During an interview this past week with the St. Louis Post-Dispatch, Shawn Hornbeck sported two fresh tattoos on his forearms. One says "respect" and the the other "faith."
They're the bywords of a 21-year-old who's been through hell and lived to tell about it.
When he was 11, Hornbeck was kidnapped while riding his bike near his Kirkwood, Missouri, home. For the next four years, he was held captive and sexually abused by a pizzeria manager Michael Devlin. Folks believed him when Devlin presented Shawn as his son.
On December 1, 2005, someone identifying himself as Shawn Devlin of Kirkwood posted a message on a Web site that Shawn's parents had set up, www.shawnhornbeck.com. It read, "how long are you planing (sic) to look for your son?" Later that day, the same person apparently posted a new message apologizing for the previous one and asking whether it would be OK to write a poem for Shawn Hornbeck.
Two police officers who frequented the pizzeria where Devlin worked ran into him, as he was taking out trash from his apartment, the officers said.
They asked him about his white truck, which was similar to a vehicle investigators were seeking in the kidnapping of another missing boy, Ben Ownby. Police were disturbed by Devlin's demeanor, and they alerted the FBI. When investigators returned to Devlin's apartment, they find not only Shawn, but Ben as well.
More than seven years has passed since Hornbeck regained his freedom.
"My life right now is actually pretty normal," he told the Post-Dispatch. He's living with his parents in Richwoods, Missouri, and working a full-time factory job. He's waiting for the right time to return to college and finish a degree in criminal law. He calls the survival of the Cleveland victims a "miracle."
Speaking out to offer them support through the media "makes me feel better as a person," Hornbeck told the paper. He said he wants to "help as much as I can."
The hardest part of their recovery, Hornbeck said, will be reconnecting. "They're going to be scared to go out in public for a while."
"They just gotta know that their family is going to be there for them and there's nothing to be afraid of."
Patricia Hearst: 'In a way, you've given up'
Arguably the most infamous abduction of the 1970s targeted newspaper heiress Patricia Hearst. Hearst was a 19-year-old student at UC Berkeley in 1974 when she was kidnapped from her apartment, imprisoned in a closet, sexually assaulted and forced to participate in a bank robbery. She was held for 84 weeks before she and her captors -- revolutionaries who called themselves the Symbionese Liberation Army -- were arrested by the FBI.
Hearst was tried, convicted and served 22 months of a 35-year original prison sentence that was commuted by President Jimmy Carter. President Bill Clinton pardoned her in 2001. After prison, Hearst married, had two children, acted in several Hollywood films and won an award with her French bulldog at the 2008 Westminster Dog Show. Now 59, she uses her married name, Patricia Hearst Shaw.
As a captive, "You have been so abused and so robbed of your free will and so frightened that you come to a point that you believe any lie that your abductor has told you," Hearst told CNN's Larry King in 2003. "You don't feel safe. You think that either you will be killed if you reach out for help, or you believe your family will be killed."
"You've, in a way, given up, you've absorbed the new identity they've given you. You're surviving -- you're not even doing that -- you're just living while everything else is going on around you," she said.
She didn't really feel free, Hearst said, until she faced her abductors in court. Then she "knew for sure that they could never, ever hurt me again."
Carlina White: Snatched as an infant
Some of the nation's youngest kidnapping victims may not even realize their dark pasts.
Before 2011, Atlanta resident Carlina Renae White had no idea that a woman posing as a nurse abducted her at a hospital in New York's Harlem neighborhood when she was just 3 weeks old. White had always had a nagging feeling that she was raised by a family to which she did not belong, said Ernie Allen from the National Center for Missing and Exploited Children.
White grew suspicious when the woman who raised her could not provide her with a birth certificate. She found her own baby picture on the national center's website and eventually learned the truth. There was a DNA test, and White reconnected with her biological family in an emotional reunion in January 2011. "I never gave up hope," White's grandmother, Elizabeth White, told WABC. "It is like she has been around us all her life. She wasn't a stranger. She fit right in."
White's surprise lead to a similar discovery by Philadelphia software salesman Steve Carter. Carter, who's in his mid-30s, was adopted at age 4 from an orphanage in Honolulu. White's story inspired him to check www.missingkids.com, where he was shocked to find his own face in a photo staring back at him. He contacted the Honolulu Police Department and later underwent a DNA test.
Police determined that three decades earlier, Carter's biological mother, Charlotte Moriarty, took him for a walk and didn't return. His biological father Mark Barnes filed a missing persons report.
Carter says he believes Moriarty put him in the Hawaiian orphanage and told authorities his name was Tenzin Amea. CNN could not independently confirm that account.
Now Carter knows his birth name: Marx Panama Moriarty Barnes.
It was, as Carter put it, "a happy ending to a story that usually isn't a happy ending."
Two of the most heinous child abductions in recent years took place in Austria.
In 1998, 10-year-old Natascha Kampusch was abducted while walking to school. Her 2010 autobiography "3,096 Days" describes the relationship she fostered with her abductor Wolfgang Priklopil. Kampusch wrote how she endured Priklopil's bizarre routines to save her own life.
The book, which was serialized in the UK's Daily Mail newspaper, details how Kampusch was locked inside a "hermetically sealed" concrete jail.
She wrote about being beaten as many as 200 times a week -- until she heard her own spine "snap."
She recalls how she was manacled to Priklopil while they slept together in his bed.
Kampusch escaped in August 2006 when she was 18. In 2010, she was reportedly living in Vienna. Priklopil, 44, an engineer, committed suicide shortly after Kampusch's escape.
In the years after her escape, Kampusch became a media personality, appearing on television shows around the world. She worked for a while as a television presenter in Austria in 2007.
Two years after Kampusch's escape, the world learned about the fate of Austrian teen captive Elisabeth Fritzl.
In 1984, her own father, Josef Fritzl, threw Elisabeth -- then 18 -- into a specially designed cellar, said prosecutors. He told other family members Elisabeth had run away to join a cult.
Josef Fritzl kept his daughter locked in the basement for the next 24 years, authorities believe, repeatedly sexually assaulting her. During that time, he fathered Elisabeth's seven children.
Fritzl's dungeon remained secret until April 2008, when Elisabeth's 19-year-old daughter, Kerstin, became seriously ill and was taken to a hospital. Hospital staff became suspicious and alerted police, who then discovered the cellar.
At a 2009 trial, jurors found Josef Fritzl guilty of rape and imprisonment and sentenced him to life in prison.
Elisabeth Fritzl and her children were given new identities by the state. They also received a pension and and a home in an undisclosed location in rural Austria, according to a report in The Sun.
Katie Beers: Foster family 'instrumental'
Katie Beers was only 9 in 1992 when neighbor John Esposito kidnapped her and locked her in his Long Island, New York, dungeon.
Esposito imprisoned Beers there for 17 days, sexually assaulting her repeatedly. She was chained by the neck in a locked wooden box suspended above the ground. A television in the corner provided the only distraction and the only light. Her only meals were junk food. Her captor broke down, and she was rescued.
Now a 30-year-old married mother of two living in rural Pennsylvania, Beers reveals details of her ordeal in her autobiography, "Buried Memories: Katie Beers' Story."
Beers describes the life of abuse she led before her kidnapping.
"My childhood consisted of enslavement by my godmother and my godmother's husband," she told CNN's Soledad O'Brien. "Not only that," she continues, "but also sexual abuse by my godmother's husband; verbal, physical and emotional abuse by both my godmother herself and her husband; and neglect by my mother."
After her rescue, Beers lived with a foster family, who she says was "instrumental" to her recovery.
"Personally, what my foster parents did for me was they kept me secluded and kept me out of the public eye for so long, and that gave me the ability to recover," Beers told New York radio station 1010 WINS.
Now that the trauma is behind them, should the three Cleveland survivors look back?
It depends on their personality.
Some, such as Beers, will refuse to speak of it again. "I try not to think about it," she said. "There's no point in thinking about the past. I've gone through therapy. I've said my piece."
"I tend to believe as a therapist that this is less helpful," said Bonnie Forrest.
Instead, "you have to come to believe that it wasn't your fault and that you made the best choices at the time to survive -- no matter what that took," she said. "Survival is something to be proud of -- proud that you have those resources -- and you go on."
For Smart, being happy offers the best punishment for her abductor.
"By dwelling on the past and holding on to the pain and the hurt that you've had to go through, that's only allowing him to steal more of your life away from you and he doesn't deserve that."
There's no looking back. She's facing forward, pointed toward the rest of her life.
CNN's Ann O'Neill, Nina Melendez, Thair Shaikh, Diana Magnay, Frederik Pleitgen, Sabrina Kahn and Stephanie Elam contributed to this report.