Internment is the imprisonment of people, commonly in large groups, without charges^[1] or intent to file charges,^[2] and thus no trial. The term is especially used for the confinement "of enemy citizens in wartime or of terrorism suspects".^[3] Thus, while it can simply mean imprisonment, it tends to refer to preventive confinement rather than confinement after having been convicted of some crime. Use of these terms is subject to debate and political sensitivities.^[4]

Interned persons may be held in prisons or in facilities known as internment camps, also known as concentration camps. This involves internment generally, as distinct from the subset, extermination camps, popularly referred to as death camps.

Internment also refers to a neutral country's practice of detaining belligerent armed forces and equipment on its territory during times of war under the Hague Convention of 1907.^[5]

The Universal Declaration of Human Rights restricts the use of internment. Article 9 states that "No one shall be subjected to arbitrary arrest, detention or exile."^[6]

The American Heritage Dictionary defines the term concentration camp as: "A camp where persons are confined, usually without hearings and typically under harsh conditions, often as a result of their membership in a group which the government has identified as dangerous or undesirable."^[7]

Although the first example of civilian internment may date as far back as the 1830s,^[8] the English term concentration camp was first used in order to refer to the reconcentrados (reconcentration camps) which were set up by the Spanish military in Cuba during the Ten Years' War (1868–78).^[9] and similar camps were set up by the United States during the Philippine–American War (1899–1902).^[10] The term concentration camp saw wider use as the British set up camps during the Second Boer War (1899–1902) in South Africa for interning Boers^[9][11] and in Kenya during the Mau Mau Uprising (1952–1960) for holding and torturing Kenyans.^[12][13] Concentration camps were also set up in Chile during the military dictatorship of Augusto Pinochet (1973–1990).^[14]

During the 20th century, the arbitrary internment of civilians by the state reached its most extreme form with the establishment of the Nazi concentration camps (1933–45). The Nazi concentration camp system was extensive, with as many as 15,000 camps^[15] and at least 715,000 simultaneous internees.^[16] The total number of casualties in these camps is difficult to determine, but the deliberate policy of extermination through labor in many of the camps was designed to ensure that the inmates would die of starvation, untreated disease and summary executions within set periods of time.^[17] Moreover, Nazi Germany established six extermination camps, specifically designed to kill millions, primarily by gassing.^[18][19]

As a result, the term "concentration camp" is sometimes conflated with the concept of an "extermination camp" and historians debate whether the term "concentration camp" or the term "internment camp" should be used to describe other examples of civilian internment.^[4]

Some international media reports have claimed that as many as 3 million Uyghurs and members of other Muslim minority groups are being held in China's re-education camps which are located in the Xinjiang region.^[20]