The October Revolution, also known as the Bolshevik Revolution, refers to a revolution—as part of the Russian Revolution—that begins with an armed insurrection in Petrograd (regarded by some as a coup d'état) traditionally dated to October 25, 1917 (November 7, N.S.).

It is the second phase of the overall Russian Revolution of 1917, after the February Revolution of the same year.

The October Revolution overthrows the Russian Provisional Government and gives the power to the Soviets dominated by Bolsheviks.

It will be followed by the Russian Civil War (1917–1922) and the creation of the Soviet Union in 1922.The revolution is led by the Bolsheviks.

Bolshevik troops begin the takeover of government buildings on October 24; however, October 25 is the date when the Winter Palace (the seat of the Provisional government located in Petrograd, then capital of Russia), is captured.