The official name for modern-day Russia under the Communist Party from 1936 to 1991 (from 1918 to 1937, according to the Constitution of the RSFSR, called the Russian Socialist Federative Soviet Republic). Part of the USSR from 1922 to 1991.
The unofficial term used for the former Russian Republic for a short period after its collapse - from 7 November 1917 (October Revolution) to 19 July 1918 (1st RSFSR Constitution) or to 30 December 1922 (Treaty on the Creation of the USSR). Also used to refer to the Soviet Union as a whole in the early stages.
RSFSR (the Russian Soviet Federative Socialist Republic) (1917–1991), largest republic of the USSR.
Soviet Union