Why are millions of people still trapped in slavery?

Slavery is illegal in every corner of the world, yet an estimated 21 million people are enslaved globally. To put that number in perspective, there are more slaves in contemporary society than at the height of the transatlantic slave trade. How is this possible? And would you even recognise a modern slave if you saw one in the street? Subscribe to The Guardian ► http://ift.tt/16bR3Lu Become a Guardian supporter ► http://bit.ly/GDNmembers The Guardian ► http://ift.tt/1AFLGzy Suggested videos: Erica: Man Made ► http://bit.ly/EricaManMade Battle for Mosul ► http://bit.ly/MosulDoc Radical Brownies ► http://bit.ly/RadicalBrowniesFilm Desert Fire ► http://bit.ly/DesertFire 6x9: experience solitary confinement ► http://bit.ly/6x9gdn Gun Nation ► http://bit.ly/GunNationDoc We Walk Together ► http://bit.ly/WeWalkTogetherFilm The last job on Earth ► http://bit.ly/LastJobOnEarth Patrick Stewart: the ECHR and us ► http://bit.ly/PatrickStewartS Guardian playlists: Guardian Bertha Documentaries ► http://bit.ly/GuardianBertha In my opinion ► http://bit.ly/InMyOpinion Owen Jones meets ► http://bit.ly/CorbynJones US elections 2016 ► http://bit.ly/elections2016gdn Guardian Animations & Explanations ►http://is.gd/explainers Guardian Investigations ► http://ift.tt/16bR6qK The Guardian's YouTube channels: Owen Jones talks ► http://bit.ly/subsowenjones Guardian Football ► http://ift.tt/1yECE17 Guardian Science and Tech ► http://ift.tt/16bR3Ly Guardian Culture ► http://ift.tt/16bR6H2 Guardian Wires ► http://ift.tt/1J9JUwL