Contemporary slavery, also known as modern slavery, refers to the institutions of slavery that continue to exist in the present day. Estimates of the number of slaves today range from around 21 million to 46 million.
The Office to Monitor and Combat Trafficking in Persons agency of the United States Department of State says that "'modern slavery', 'trafficking in persons', and 'human trafficking' have been used as umbrella terms for the act of recruiting, harboring, transporting, providing or obtaining a person for compelled labor or commercial sex acts through the use of force, fraud, or coercion". Besides these, a number of different terms are used in the US federal Victims of Trafficking and Violence Protection Act of 2000 and the Protocol to Prevent, Suppress and Punish Trafficking in Persons, especially Women and Children, including "involuntary servitude", "slavery" or "practices similar to slavery", "debt bondage", and "forced labor".
According to American professor Kevin Bales, co-founder and former president of Free the Slaves, modern slavery occurs "when a person is under control of another person, who applies violence and force to maintain that control, and the goal of that control is exploitation". According to this definition, research from the Walk Free Foundation based on its Global Slavery Index 2016 estimated that there were about 45.8 million slaves around the world in 2016, with 58% of them living in the top five countries—India, Pakistan, China, Bangladesh, and Uzbekistan. Of these 45.8 million, it is estimated that around 10 million of these contemporary slaves are children. Bales warned that, because slavery is officially abolished everywhere, the practice is illegal, and thus more hidden from the public and authorities. This makes it impossible to obtain exact figures from primary sources. The best that can be done is estimate based on secondary sources, such as UN investigations, newspaper articles, government reports, and figures from NGOs.
Slaves can be an attractive investment because the slave-owner only needs to pay for sustenance and enforcement. This is sometimes lower than the wage-cost of free laborers, as free workers earn more than sustenance; in these cases, slaves have a positive price. When the cost of sustenance and enforcement exceeds the wage rate, slave-owning would no longer be profitable, and owners would simply release their slaves. Slaves are thus a more attractive investment in high-wage environments, and environments where enforcement is cheap, and less attractive in environments where the wage-rate is low and enforcement is expensive.
Free workers also earn compensating differentials, whereby they are paid more for doing unpleasant work. Neither sustenance nor enforcement costs rise with the unpleasantness of the work, however, so slaves' costs do not rise by the same amount. As such, slaves are more attractive for unpleasant work, and less for pleasant work. Because the unpleasantness of the work is not internalised, being borne by the slave rather than the owner, it is a negative externality and leads to over-use of slaves in these situations. Slaves can also be forced to do illegal work such as pick pocketing, or cannabis production.
Modern slavery can be quite profitable and corrupt governments tacitly allow it, despite it being outlawed by international treaties such as Supplementary Convention on the Abolition of Slavery and local laws. Total annual revenues of traffickers were estimated in 2004 to range from US $5 billion to US $9 billion, though profits are substantially lower. American slaves in 1809 were sold for around the equivalent of US$40,000 in today's money. Today, a slave can be bought for $90. The conscription of child soldiers by some governments is often viewed as a form of government-endorsed slavery.
Modern slavery is often seen as a by-product of poverty. Countries that lack education, economic freedom, the rule of law, and have poor societal structure can create an environment that fosters the acceptance and propagation of slavery.
Professor Remington Crawford III of the University of Toronto said:
Slavery is something that's with us always. We need to keep it in view and think about it when we buy our clothes, to question where they are sourced. Governments and CEOs need to think more carefully about what they are doing and what they are inadvertently supporting.
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This is the form most often associated with the word "slavery". It stems historically from either conquest, where a conquered person is enslaved, as in the Roman Empire, or from slave raiding, as in the Atlantic slave trade or Arab slave trade.
Millions of people today work as bonded laborers. The cycle begins when people take extreme loans under the condition that they work off the debt. The "loan" is designed so that it can never be paid off, and is often passed down for generations. This form of slavery is prevalent in South Asia. People become trapped in this system working ostensibly towards repayment though they are often forced to work far past the original amount they owe. They work under the force of threats and abuse, their helplessness is reinforced due to the large power differential between the "creditor" and the "debtor".
People may be enticed to migrate with the promise of work, only to have their documents seized and be forced to work under the threat of violence to them or their families. Undocumented immigrants may also be taken advantage of; without legal residency, they often have no recourse to the law. Along with sex slavery, this is the form of slavery most often encountered in wealthy countries such as the United States, in Western Europe, and in the Middle East.
Along with migrant slavery, forced prostitution is the form of slavery most often encountered in wealthy regions such as the United States, in Western Europe, and in the Middle East. It is the primary form of slavery in Eastern Europe and Southeast Asia, particularly in Moldova and Laos. Many child sex slaves are trafficked from these areas to the West and the Middle East. An estimated 22% of slaves to date are active in the sex industry.
Mainly driven by the culture in certain regions, early or forced marriage is a form of slavery that affects millions of women and girls all over the world. When families cannot support their children, the daughters are often married off to the males of wealthier, more powerful families. These men are often significantly older than the girls. The females are forced into lives whose main purpose is to serve their husbands. This often fosters an environment for physical, verbal and sexual abuse.
Children comprise about 26% of the slaves today. Most are domestic workers or work in cocoa, cotton or fishing industries. Many are trafficked and sexually exploited. In war-torn countries, children have been kidnapped and sold to political parties to use as child soldiers. Forced child labor is the dominant form of slavery in Haiti.
In addition to sex slavery, modern slaves are often forced to work in certain occupations. Common occupations include:
Signs that someone may have been forced into slavery include a lack of identity documents, lack of personal possessions, clothing that is unsuitable or has seen much wear, poor living conditions, a reluctance to make eye contact, unwillingness to talk, and unwillingness to seek help. In the UK people are encouraged to report suspicions to a modern slavery telephone helpline.
The United Nations have defined human trafficking as follows:
The recruitment, transportation, transfer, harbouring or receipt of persons, by means of the threat or use of force or other forms of coercion, of abduction, of fraud, of deception, of the abuse of power or of a position of vulnerability or of the giving or receiving of payments or benefits to achieve the consent of a person having control over another person, for the purpose of exploitation. Exploitation shall include, at a minimum, the exploitation of the prostitution of others or other forms of sexual exploitation, forced labor or services, slavery or practices similar to slavery, servitude or the removal of organs.
According to United States Department of State data, an "estimated 600,000 to 820,000 men, women, and children [are] trafficked across international borders each year, approximately 70 percent are women and girls and up to 50 percent are minors. The data also illustrates that the majority of transnational victims are trafficked into commercial sexual exploitation." However, "the alarming enslavement of people for purposes of labor exploitation, often in their own countries, is a form of human trafficking that can be hard to track from afar". It is estimated that 50,000 people are trafficked every year in the United States.
The governments credited with the strongest response to modern slavery are the Netherlands, the United States, the United Kingdom, Sweden, Australia, Portugal, Croatia, Spain, Belgium, Germany and Norway. In the United kingdom, the government has instituted major reforms in the legal system through the Criminal Finance Act effective from September 30,2017.Under the act, there will be transparency in regards to interbank information sharing with law enforcement agencies to help on the crackdown of money laundering agencies related to contemporary slavery. The Act also aims at reducing the incidence of tax evasion attributed to the lucrative slave trade conducted under the domain of the law. 
English and Welsh police have been accused of doing too little and of not handling victims in ways that encourage them to explain what has happened. There are also legal difficulties in defining crimes and prosecuting perpetrators.
In contrast, the governments accused of taking the least action against it are North Korea, Iran, Eritrea, Equatorial Guinea, Hong Kong, Central African Republic, Papua New Guinea, Guinea, the Democratic Republic of the Congo and South Sudan.
Modern slavery is a multibillion-dollar industry with estimates of up to $35 billion generated annually.[needs update] In 2013 the United Nations estimated that roughly 27 to 30 million individuals are currently caught in the slave trade industry. According to Walk Free Foundation, there were 46 million people worldwide enslaved in 2016 in the form of "human trafficking, forced labor, bondage from indebtedness, forced or servile marriage or commercial sexual exploitation", with an estimated 18 million of those in India. China is second with 3.4 million, followed by Pakistan (2.1 million), Bangladesh (1.5 million), and Uzbekistan (1.2 million). By percentages of the population living in slavery Uzbekistan tops with 4% of its population living under slavery followed by Cambodia (1.6%), India, (1.4%) and Qatar (1.4%). Although these figures have also faced criticism for its inconsistency and questionable methodology.
Slavery also exists in advanced democratic nations, for example the UK where Home Office estimates suggested 10,000 to 13,000 victims in December 2015.[needs update] This includes, forced work of various kinds, such as forced prostitution. The UK has recently made an attempt to combat modern slavery via the Modern Slavery Act 2015. Large commercial organisations are now required to publish a slavery and human trafficking statement in regard to their supply chains for each financial year.
Fifteen migrant workers from Burma and Cambodia also told how they had been enslaved.