Captivity, or being held captive, is a state wherein humans or other animals are confined to a particular space and prevented from leaving or moving freely. An example in humans is imprisonment. Prisoners of war are usually held in captivity by a government hostile to their own. Animals are held in captivity in zoos, and often as pets and as livestock. Captivity, or being held captive, is a state wherein humans or other animals are confined to a particular space and prevented from leaving or moving freely. An example in humans is imprisonment. Prisoners of war are usually held in captivity by a government hostile to their own. Animals are held in captivity in zoos, and often as pets and as livestock. Captivity is the state of being captive, of being imprisoned or confined.:260:32 The word derives from the late Middle English captivitas, and the Latin captivus and capere, meaning to seize or take,:260 which is also the root of the English word, 'capture'. In humans, captivity may include arrest and detention as a function of law enforcement and a civilian correctional system, detention of combatants in a time of war, as well as human trafficking, slave taking, and other forms of involuntary confinement, forced relocation, and servitude.:246:1:Ch.1 In non-human animals, captivity may include confinement for the purpose of food production or labor, such as that done on a farm, confinement for the purpose of human recreation or education, such as that done at a zoo or aquarium, or confinement for the purpose of keeping domesticated pets, such as that commonly done with animals such as the house cat or the dog.:1-4 In relation to non-living objects, captivity may describe the state of having control, whether that be control of one person over an object, such as 'capturing a piece' in the game of chess, the control of a group over an area, such as the 'capture' of a fort or city during a time of war, or control exercised by one object over another, such as one celestial body being 'captured' by the gravitational pull of another, or a 'captive balloon' which is tethered to the ground by a rope or string.:260 In a philosophical sense, captivity may refer not simply to confinement or lack of individual freedom, but also to the nature of a relationship between the captive and the captor, characterized by a lack of self-direction and autonomy.:248-49 'Although the paradigm case of captivity is a free person who is held against her will by another, the existence of captive children and animals makes it clear that the denial of autonomy as it is usually understood is not a condition for captivity'. In some instances, the captivity of the subject is clear, as with an animal kept in a cage at a zoo. However, circumstances exist under which captivity is more amorphous. For example, it has been noted that it is hard to say whether members of a rhinoceros family kept in a thousand-acre enclosure within their normal area of habitation, for purposes of insuring their preservation, are really in captivity.:2 Captivity may also be employed in more abstract or figurative senses, such as to captivate, meaning to subdue through charm, or to capture such as an artist attempting to 'capture a mood', or 'capture a scene'.:260:32:246 Humans are held captive under the authority of their own government for a number of different reasons. Under certain circumstances, a person suspected of committing a crime is subject to detention for a period of time while awaiting trial for that crime. In some cases, a person may be detained and then released without being charged with criminal wrongdoing. Persons convicted of a crime may sent to a prison. According to the Institute for Criminal Policy Research at the University of London, as of 2016 an estimated 10.35 million people were imprisoned worldwide. Throughout human history, the practice of 'captive taking' during war was commonly practiced. Those taken from the defeated group, most often women and children, would typically be enslaved, sold into slavery to others, forced to marry members of the victorious group, or held in permanent sexual captivity. The first Roman gladiators, for example, were prisoners of war. The taking of captives may have been a byproduct, but was also often a primary goal of conducting raids and warfare in small scale societies.:1-7 According to some estimates of ancient societies, war captives and slaves may have at various points comprised as much as 20% of Roman Italy, 33% of Greece, 70% of Korea, 20% of some Islamic states, 40% of tropical American societies, and as much as half of some African societies.:8-9 The practice of conducting raids for captive taking extended in some forms until modern times, for example, piracy in the Mediterranean Sea and the taking of captives to be sold as slaves continued until the 19th century, when it eventually culminated in the Barbary Wars. Over time, nations found it to be in their interests to agree to international standards regarding the treatment of captured soldiers. The 1648 Peace of Westphalia, which ended the Thirty Years' War, established that prisoners of war should be released without ransom at the end of hostilities and that they should be allowed to return to their homelands. Chapter II of the Annex to the 1907 Hague Convention IV – The Laws and Customs of War on Land covered the treatment of prisoners of war in detail. These provisions were further expanded in the 1929 Geneva Convention on the Prisoners of War and were largely revised in the Third Geneva Convention in 1949. Article 4 of the Third Geneva Convention protects captured military personnel, some guerrilla fighters, and certain civilians. It applies from the moment a prisoner is captured until he or she is released or repatriated. One of the main provisions of the convention makes it illegal to torture prisoners and states that a prisoner can only be required to give their name, date of birth, rank and service number (if applicable).