The Bolshevik Party was a revolutionary political group in Russia, founded in 1903 as a faction of the Russian Social Democratic Labor Party. Led by Vladimir Lenin, the Bolsheviks advocated for a socialist government and aimed to overthrow the existing Tsarist regime. They believed in a vanguard party to lead the working class toward revolution. In 1917, the Bolsheviks played a crucial role in the October Revolution, which resulted in the overthrow of the provisional government. Following this, they established the Russian Soviet Federative Socialist Republic, marking the beginning of communist rule in Russia. The party later became the dominant force in the Soviet Union.