An internment camp was a type of prison where groups of people considered enemies of the state were confined.
During World War II on Earth, the United States imprisoned its Japanese-American population in internment camps such as Manzanar.
Star Trek: The Original Series actor George Takei, a Japanese-American, was held with his family in an internment camp located in Arkansas when he was a child.
During their conflict with the Cabal in the 2150s, the Tandarans established internment camps to house their resident Suliban population regardless of whether they were aligned with the Cabal. One such camp was Detention Complex 26. Based on Earth's historical experience, Captain Jonathan Archer decided to liberate the camp in 2152. (ENT: "Detained")
During the Occupation of Bajor, the Cardassians also operated such camps, such as the Velos VII internment camp. (DS9: "Babel")
The Dominion operated internment camps such as Internment Camp 371, where a number of individuals from the Alpha Quadrant were held in 2373. (DS9: "In Purgatory's Shadow") Ishka was briefly held at an internment center after her capture by the Dominion in 2374. (DS9: "The Magnificent Ferengi")