Professor Kevin Bales, co-founder of Free the Slaves, explains to Max Foster how his organization calculates the total number globally - and says 30 million is a conservative figure.
Bales examines how different countries face the problem, and explains why Brazil is setting the best example.
Slavery is all over the world, not just developing countries. The film "Eden" is based on Chong Kim's story as a sex slave in U.S. Here she tells Becky Anderson how members of the public stood and did nothing when she tried to run away, and how she plotted her eventual escape.
Sophie Hayes' love story started out like so many Hollywood rom-coms. He was a man she knew and trusted, and who knew everything about her, what made her laugh and cry and what her favorite song was. He was there for her when she had bad days, a quick phone call away in times of trouble. She was just a normal girl and he a normal guy.
But this love story turned into a horror story on a holiday with the man she had grown to love. Forced to work on the streets as a prostitute, emotionally isolated, miles from her British home, suffering mental and physical abuse, rape, and torture.
Anti-slavery campaigner Sophie Hayes has released a powerful campaign to draw attention to the dangers of women who get lured into relationships, only to lose their freedom. Women like her.
A report claiming to be the most comprehensive look at global slavery says 30 million people are living as slaves around the world.
The Global Slavery Index, published by the Australia-based Walk Free Foundation, lists India as the country with by far the most slaves, with an estimated nearly 14 million, followed by China (2.9 million) and Pakistan (2.1 million).
The top 10 countries on its list of shame accounted for more than three quarters of the 29.8 million people living in slavery, with Nigeria, Ethiopia, Russia, Thailand, Democratic Republic of Congo, Myanmar and Bangladesh completing the list.
CNN is joining the fight to end modern-day slavery by shining a spotlight on the horrors of modern-day slavery, amplifying the voices of the victims, highlighting success stories and helping unravel the complicated tangle of criminal enterprises trading in human life. WHY WE'RE DOING THIS | MORE ABOUT THE PROJECT