File:CCCP (Soviet) Passport, 1995 (8674948308).jpg

СССР (Союз Советских Социалистических Республик ) is a Russian (Cyrillic) abbreviation for the Soviet Union.

The Union of Soviet Socialist Republics (Russian: Сою́з Сове́тских Социалисти́ческих Респу́блик, tr. Soyuz Sovetskikh Sotsialisticheskikh Respublik) abbreviated to USSR (Russian: СССР, tr. SSSR) or the Soviet Union (Russian: Советский Союз, tr. Sovetsky Soyuz), was a constitutionally communist state that existed between 1922 and 1991, ruled as a single-party state by the Communist Party with Moscow as its capital. A union of multiple subnational Soviet republics, its government and economy were highly centralized.

The Soviet Union had its roots in the Russian Revolution of 1917, which deposed the imperial autocracy. The Bolsheviks, led by Vladimir Lenin, then overthrew the Provisional Government. The Russian Socialist Federative Soviet Republic was established and the Russian Civil War began. The Red Army entered several territories of the former Russian Empire and helped local communists seize power. In 1922, the Bolsheviks were victorious, forming the Soviet Union with the unification of the Russian, Transcaucasian, Ukrainian and Byelorussian republics. Following Lenin's death in 1924, a troika collective leadership and a brief power struggle, Joseph Stalin came to power in the mid-1920s. Stalin committed the state ideology to Marxism–Leninism and initiated a centrally planned economy. As a result, the country underwent a period of rapid industrialisation and collectivisation which laid the basis for its later war effort and dominance after World War II. However, Stalin repressed both Communist Party members and elements of the population through his authoritarian rule.

During the first phase of World War II, Soviet Union used the opportunity to acquire territories in Eastern Europe adjacent to Nazi Germany, its satellites, and their occupied territories. Later in 1941, Nazi Germany invaded the Soviet Union, opening the largest and bloodiest theatre of war in history and violating an earlier non-aggression pact between the two countries. The Soviet Union suffered the largest loss of life in the war, but halted the Axis advance at intense battles such as that at Stalingrad, eventually driving through Eastern Europe and capturing Berlin in 1945. Having played a decisive role in the Allied victory in Europe, the Soviet Union established the Eastern Bloc in much of Central and Eastern Europe and emerged as one of the world's two superpowers after the war. Together with these new satellite states, through which the Soviet Union established economic and military pacts, it became involved in the Cold War, a prolonged ideological and political struggle against the Western Bloc, led by the other superpower, the United States.

A de-Stalinization period followed Stalin's death, reducing the harshest aspects of society. The Soviet Union then went on to initiate significant technological achievements of the 20th century, including launching the first ever satellite and world's first human spaceflight, which led it into the Space Race. The 1962 Cuban Missile Crisis marked a period of extreme tension between the two superpowers, considered the closest to a mutual nuclear confrontation. In the 1970s, a relaxation of relations followed, but tensions resumed with Soviet invasion of Afghanistan in 1979. The occupation drained economic resources and dragged on without achieving meaningful political results.