The Gulag (Russian: ГУЛАГ, tr. GULAG; IPA: [ɡʊˈlak]; acronym of Главное управление лагерей, Glavnoye Upravleniye LAGerej, lit. "Main Camp Administration") was the government agency that administered and controlled the Soviet forced-labor camp system during Joseph Stalin's rule from the 1930s up until the 1950s. The term is also commonly used to reference any forced-labor camp in the Soviet Union. The camps housed a wide range of convicts, from petty criminals to political prisoners. Large numbers were convicted by simplified procedures, such as NKVD troikas (secret police) and other instruments of extrajudicial punishment. The Gulag is recognized as a major instrument of political repression in the Soviet Union.
The agency's full name was the Main Administration of Corrective Labor Camps and Labor Settlements (Гла́вное управле́ние исправи́тельно-трудовы́х лагере́й и коло́ний, Glavnoye upravleniye ispravityelno-trudovykh lagerey i koloniy). It was administered first by the State Political Administration (GPU), later by the NKVD and in the final years by the Ministry of Internal Affairs (MVD). The Solovki prison camp, the first corrective labour camp constructed after the revolution, was established in 1918 and legalized by a decree "On the creation of the forced-labor camps" on April 15, 1919 (Article 58 of the Russian SFSR penal code). The internment system grew rapidly, reaching a population of 100,000 in the 1920s and from the very beginning it had a very high mortality rate.