The October Revolution, also known as the Great October Socialist Revolution, October coup, or Bolshevik coup was a revolution in Russia led by the Bolshevik Party of Vladimir Lenin that was a key moment in the larger Russian Revolution of 1917–1923. It was the second revolutionary change of government in Russia in 1917. It took place through an armed insurrection in Petrograd on 7 November 1917 [O.S. 25 October]. It was the precipitating event of the Russian Civil War.

The Russian Revolution was a period of political and social change in the Russian Empire, starting in 1917. This period saw Russia abolish its monarchy and adopt a socialist form of government following two successive revolutions and a bloody civil war. The Russian Revolution can also be seen as the precursor for the other European revolutions that occurred during or in the aftermath of World War I, such as the German Revolution of 1918–1919.