There are different ways that people end up being trafficked. The biggest producers of cocoa are Ghana and Ivory Coast and it's not unusual for children from neighbouring countries to be sold by a family member to a plantation. While there, they receive no education. When they become adults, it's more expensive to keep them, so they're let go and replaced with more children.

Most organisations tend to use inflated numbers to sensationalise the scale of the problem, but getting reliable data is difficult. When I first began researching the subject, many NGO's were claiming that there were 27.5 million people who were modern-day slaves, whereas the figure from the UN was closer to 2.5 million.

Finding people who are trafficked is relatively easy. When you hear their stories, patterns begin to emerge very quickly. Traffickers approach people who are living in poverty with a solution to their economic woes, promising a job for them or a family member. The reality turns out to be quite different from the story.

There's waaaay more information online now than there used to be. I'd recommend approaching it with scepticism, but you'll get a general idea.