Debt bondage

The status or condition of a person who is in debt because of a pledge for labor or service. That labor or service needs to be applied to retiring that debt.

Human smuggling

Helping someone illegally enter a country, often without identification or papers, for financial or material benefit. Victims can be recruited in the same way as those who are trafficked. Often, those sneaking into a country are put at great risk, and some die.

Human trafficking

Recruiting, kidnapping, coercing or selling someone for the purposes of a commercial sex act or labor. Trafficking can occur within a country or across international borders.

Involuntary servitude

Forcing or keeping a person working through threats, harm, physical abuse, restraint or legal retaliation.

Sweatshop

A factory, often crowded, unsanitary and dangerous, in which employees are exploited by working long hours at poor wages and are threatened with physical and verbal abuse. The word stems from the 19th century, when subcontractors paid their employees for their "sweat."

Sources:
Seattle PI [1]
SweatFree [2]