The former Soviet Union, officially known as the Union of Soviet Socialist Republics (USSR), was a federation of multiple republics that existed from 1922 until its dissolution in 1991. It was a major world power during the 20th century, known for its communist government and significant influence in global politics, economics, and culture. The Soviet Union comprised 15 republics, including Russia, Ukraine, and Belarus. It played a crucial role in events such as World War II and the Cold War. After its collapse, many of the republics became independent nations, leading to significant political and economic changes in the region.