<P> Slavery began to exist before written history, in many cultures . A person could become enslaved from the time of their birth, capture, or purchase . </P> <P> Historically, slavery has been legalized institutionally in most societies at some point, but is now outlawed in all recognized countries . The last country to officially abolish slavery was Mauritania in 2007 . Nevertheless, there are an estimated 40.3 million people worldwide subject to some form of modern slavery . The most common form of modern slave trade is commonly referred to as human trafficking . In other areas, slavery (or unfree labour) continues through practices such as debt bondage, the most widespread form of slavery today, serfdom, domestic servants kept in captivity, certain adoptions in which children are forced to work as slaves, child soldiers, and forced marriage . </P> <P> The English word slave comes from Old French sclave, from the Medieval Latin sclavus, from the Byzantine Greek σκλάβος, which, in turn, comes from the ethnonym Slav, because in some early Medieval wars many Slavs were captured and enslaved . An older interpretation connected it to the Greek verb skyleúo' to strip a slain enemy' . </P> <P> There is a dispute among historians about whether terms such as "unfree labourer" or "enslaved person", rather than "slave", should be used when describing the victims of slavery . According to those proposing a change in terminology, "slave" perpetuates the crime of slavery in language, by reducing its victims to a nonhuman noun instead of, according to Andi Cumbo - Floyd, "carry (ing) them forward as people, not the property that they were". Other historians prefer "slave" because the term is familiar and shorter, or because it accurately reflects the inhumanity of slavery, with "person" implying a degree of autonomy that slavery does not allow for . </P>

In which of the following systems is raiding most prevalent