The abbreviation GULAG (?????) stands for "Glávnoye upravléniye ispravítel'no-trudovýkh lageréy" (??????? ?????????? ?????????????-???????? ??????? or "Main Directorate of Correctional Labour Camps"), but the full official name of the agency changed several times.

The Gulag is recognized as a major instrument of political repression in the Soviet Union. The camps housed both ordinary criminals and