Today, it is rare to find old forms of slavery in which people are sold at auctions. Now, slavery happens when workers spend years struggling to repay a debt or when a child does labor at no or little wages. For example, imigrants come to America hoping for a great life, but they soon realize that a great life isn't exactly an option. They come to be wealthy but are tricked into slaving for hours. Everything in the United States is expensive so they turn out working for hours, slaving away just to eat.
In West Africa, there's a booming trade in children sold as domestic servants. It's different all over the world, but it's happening.