Slavery is a legal or economic system in which principles of property law are applied to humans allowing them to be classified as property, to be owned, bought and sold accordingly, and they cannot withdraw unilaterally from the arrangement. While a person is a slave, the owner is entitled to the productivity of the slave's labour, without any remuneration. The rights and protection of the slave may be regulated by laws and customs in a particular time and place, and a person may become a slave from the time of their capture, purchase or birth.
Today, chattel slavery is unlawful in all countries, but a person may still be described as a slave if he or she is forced to work for another person without an ability on their part to unilaterally terminate the arrangement. Such situations are today commonly referred to as "practices similar to slavery". The present form of the slave trade is commonly referred to as human trafficking.
Slavery existed before written history and in many cultures. It was once institutionally recognized by most societies, but has now been outlawed in all countries, the last being Mauritania in 2007. However, it continues through such practices as debt bondage, serfdom, domestic servants kept in captivity, certain adoptions in which children are forced to work as slaves, child soldiers, human trafficking and forced marriage. Accordingly, there are more slaves today than at any time in history, with an estimated 20 million to 36 million slaves worldwide.
Slavery in the Ottoman (Turkish) Empire was a legal and important part of the Ottoman Empire's economy and society until the slavery of Caucasians was banned in the early 19th century, although slaves from other groups were allowed. In Constantinople (present-day Istanbul), the administrative and political center of the Empire, about a fifth of the population consisted of slaves in 1609. Even after several measures to ban slavery in the late 19th century, the practice continued largely unabated into the early 20th century. As late as 1908, female slaves were still sold in the Ottoman Empire.Sexual slavery was a central part of the Ottoman slave system throughout the history of the institution.
A member of the Ottoman slave class, called a kul in Turkish, could achieve high status. Harem guards and janissaries are some of the better known positions a slave could hold, but slaves were actually often at the forefront of Ottoman politics. The majority of officials in the Ottoman government were bought slaves, raised free, and integral to the success of the Ottoman Empire from the 14th century into the 19th. Many officials themselves owned a large number of slaves, although the Sultan himself owned by far the largest amount. By raising and specially training slaves as officials in palace schools such as Enderun, the Ottomans created administrators with intricate knowledge of government and fanatic loyalty.