Migrant sex work
Because of their illegal and vulnerable economic status, some migrant sex workers may find themselves in situations where coercion and forced sex work may be present. Under international legal definitions of human trafficking, forced and coercive forms of sex work are considered to be instances of involuntary sex trafficking. However, many scholars caution against categorizing sex workers as either completely voluntary or completely involuntary. They often argue that sex work, like other forms of labor, can span a spectrum between the two extremes, with most circumstances falling in the middle through various labor rights violations. Nevertheless, the vulnerability of migrant sex workers can make them susceptible to exploitative or coercive labor practices that can resemble or be human trafficking.
Prostitution
Sex trafficking is defined as using coercion or force to transport an unwilling person into prostitution or other sexual exploitation. The United Nations stated in 2009 that sex trafficking is the most commonly identified form of human trafficking and estimates that about 79% of human trafficking reported is for prostitution (although the study notes that this may be the result of statistical bias and that sex trafficking tends to receive the most attention and be the most visible). Sex trafficking has been described by Kul Gautum, Deputy Executive Director of UNICEF, as "the largest slave trade in history." It is also the fastest growing criminal industry, predicted to outgrow drug trafficking. While there may be a higher number of people involved in slavery today than at any time in history, the proportion of the population is probably the smallest in history.