Internment camps were form a prison used by the various governments of the galaxy for certain groups.
During Earth's 2nd World War, the United States operated a japanese internment camp at Manzanar for americans of japanese descent.(ENT episode: "Detained") The German/Nazis also operated internment camps which were much crueler than the americans.
In the Gamma Quadrant, the Dominion used camps for their enemies. The main law in these camps were "there is no release, no escape... except death." They also kept individuals that were replaced by Changeling infiltrators. One camp was Internment Camp 371. (DS9 episode: "In Purgatory's Shadow")