More people are slaves today than the combined populations of London, New York, Sao Paulo and Hong Kong. Trafficked into the sex trade, bonded into manual labour or born into servitude, they suffer in many prisons: brothels and brick kilns, farms and fishing boats, hotels and suburban homes.
It's a truism to say that slavery is all around. Despite the ubiquity, media coverage is often confused, sensationalist or just plain wrong.
That's why the Thomson Reuters Foundation teamed up with the International Labour Organization (ILO) to bring journalists from around the world to London for an intensive Reporting Trafficking and Slavery workshop, allowing them to deepen their knowledge of a scourge that generates $150 billion a year in illegal profits.
The reporters came from as far afield as Mauritania, Ethiopia, South Africa, India, Nepal, Pakistan, Philippines, Brazil, Argentina and Bulgaria. We brought them face-to-face with top policymakers, journalists, experts and activists.
Speakers included Kevin Hyland, Britain's first independent anti-slavery commissioner; Evelyn Chumbow, a former child slave and leader of the National Survivor Network; and investigative journalists Annie Kelly, head of the Guardian's Modern-day slavery in focus project, Benjamin Skinner, author of "A Crime So Monstrous: Face-to-Face with Modern-Day Slavery", and Leonardo Sakamoto, founder of Reporter Brasil, which investigates companies accused of using slave labour.
Over five days, the journalists tackled subjects diverse as slavery in supply chains, using data to fight slavery and the psychology of surviving slavery - staples of the Thomson Reuters Foundation's Trust Women Conference, which ran in parallel with the workshop.
They also discussed ethical issues, including dos and don'ts when it comes to interviewing traumatised survivors and how to avoid preconceived stereotypes.
Many of the reporters were long enough in the tooth to be unfazed by common myths and misconceptions, such as the belief that most slaves are in the sex industry (far more are in other forms of forced labour) or that to be trafficked you have to be shunted across a border (not true). Nor were they shocked that many slave-masters and traffickers are women.
But other revelations were a cause for surprise. Here are just six talking points that sparked lively discussion.
1. Despite years of research, slavery data is iffy and inconsistent
Add up the populations of the four cities mentioned above and you get 36 million, equivalent to the number of slaves worldwide as estimated by the Walk Free Foundation in its latest Global Slavery Index. But if you go with ILO estimates of 21 million, you'd have to use fewer (or smaller) cities to get a feel for what the statistics mean.
The discrepancy is down to different definitions of what constitutes forced labour, trafficking and slavery as well as inconsistent methodologies for guesstimating numbers.
Some activists say this data "chaos" stymies effective action and prolongs the suffering of victims. Others argue that since modern slavery is a term without a legal base, its inflationary use undermines prosecutions and trafficked peoples' rights to remedy and assistance.
Aidan McQuade, director of Anti-Slavery International, takes a more pragmatic view. "One can look at the methodologies and say this is good, bad or indifferent," he told the journalists. "The underlying truth of both sets of definitions is there's a lot of people in slavery, and the key question to ask after that is why."
2. Smuggling and trafficking are not synonyms
Reporters often use these terms interchangeably, especially in coverage of one of the year's top stories: the biggest movement of displaced people through Europe since World War Two.
Trafficking implies coercion while smuggling happens with your permission -- and probably after you've handed over a large sum of cash (though plenty of smuggled people are later preyed upon by traffickers).
"In Europe, there's no evidence that they (refugees and migrants) are being trafficked, that they're coming to Europe against their will," said Marcia Poole, ILO's director of communications.
3. Lazy language has legal consequences
Terminology matters. Many trafficking and slavery survivors find themselves criminalised, deported and even re-trafficked because they've been incorrectly classified as illegal migrants, say, or underage sex workers rather than victims of heinous crimes.
"If you're a sports journalist and you mess up when you do the reporting - you say that Real Madrid lost to Barcelona when Real Madrid won - you're doing bad journalism but you do not change the result of the game," ILO consultant Charles Autheman said.
"When you do bad journalism about migration, you can change the result of the game. It's the victims of trafficking who go back to their country, and they are put in jail because they have not been categorised as victims of trafficking but as 'irregular migrants'."
4. Only two countries have ratified a key anti-slavery treaty
Last week, Norway became the second nation - after Niger - to approve a U.N. treaty designed to give countries the legal muscle to combat forced labour and trafficking.
The protocol, which essentially modernises a forced labour convention from 1930, requires countries to change laws to prevent trafficking, protect victims and improve compensation.
To be fair, it only came into being last year. The ILO is campaigning to convince at least 50 countries to ratify the treaty by 2018.
5. Traffickers groom sex slaves like extremists groom recruits
Nazir Afzal, former Chief Crown Prosecutor for the North West of England, has prosecuted some of the highest-profile cases of sexual abuse in Britain, including gangs that "groom" vulnerable young girls for sex slavery. He described the three stages of grooming: "manipulation" (find something that's deficient in your life and promise to put it right), "distancing" (get you on your own) and "grabbing" (lock you in).
"And when I talk to anyone about extremism, grooming for ideology is the same as grooming for sex," he told the journalists. "The same system is being used by ISIS. They groom 100 hours online - everything you want, everything that's wrong with you and your life, I can fix."
6. Slavery was almost left out of Sustainable Development Goals
The first draft of new global goals to fight poverty, inequality and climate change - the most comprehensive U.N. blueprint to tackle the world's ills - didn't mention trafficking. Only a last-minute push by activists, supported by Pope Francis, secured an amendment, ensuring that the targets adopted in September include measures to eliminate slavery.
"Although many victims are enslaved within and trafficked from developing countries, to date modern slavery and development have been treated as separate policy areas," said Kevin Hyland, Britain's anti-slavery czar, who helped champion the amendment.
One example of the link between slavery and development relates to money sent home from migrant workers. "It (slavery) results in a huge loss of remittances to developing countries because remittance flows are taken from victims, who are forced to pay off debts and become profit for the criminals," he said.