While some unfree labourers, such as serfs, have substantive, de jure legal or traditional rights, they also have no ability to terminate the arrangements under which they work, and are frequently subject to forms of coercion, violence, and restrictions on their activities and movement outside their place of work.
Forced marriage continues to be practiced in parts of the world including some parts of Asia and Africa.
Forced marriages may also occur in immigrant communities in Europe, the United States, Canada and Australia.
Economists have attempted to model the circumstances under which slavery (and variants such as serfdom) appear and disappear.
One observation is that slavery becomes more desirable for landowners where land is abundant but labour is scarce, such that rent is depressed and paid workers can demand high wages.
Forced labour, or unfree labour, is sometimes used to refer to when an individual is forced to work against their own will, under threat of violence or other punishment, but the generic term unfree labour is also used to describe chattel slavery, as well as any other situation in which a person is obliged to work against their own will and a person's ability to work productively is under the complete control of another person.
This may also include institutions not commonly classified as slavery, such as serfdom, conscription and penal labour.In other areas, slavery (or unfree labour) continues through practices such as debt bondage, the most widespread form of slavery today, 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.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.Similar arguments appear later in the works of Auguste Comte, especially when it comes to Adam Smith's belief in the separation of powers, or what Comte called the "separation of the spiritual and the temporal" during the Middle Ages and the end of slavery, and Smith's criticism of masters, past and present.As Smith stated in the Lectures on Jurisprudence, "The great power of the clergy thus concurring with that of the king set the slaves at liberty.In a broader sense, however, the word slavery may also refer to any situation in which an individual is de facto forced to work against their own will.