The Bolsheviks, derived from большинство bol'shinstvo, "majority", literally meaning "one of the majority") were a faction of the Marxist Russian Social Democratic Labour Party (RSDLP) which split apart from the Menshevik faction at the Second Party Congress in 1903.
In the Second Party Congress vote, the Bolsheviks won on the majority of important issues; hence their name. They ultimately became the Communist Party of the Soviet Union. The Bolsheviks came to power in Russia during the October Revolution phase of the Russian Revolution of 1917, and founded the Russian Soviet Federative Socialist Republic which would later become the chief constituent of the Soviet Union in 1922.
Left to right: Leon Trotsky, Vladimir Lenin, and Lev Kamenev
Boris Kustodiev's 1920 painting "Bolshevik"
"Down with Bolshevism. Bolshevism brings war and destruction, hunger and death", anti-Bolshevik propaganda, Germany, 1919.
The Bolsheviks, founded by Vladimir Lenin and Alexander Bogdanov, were by 1905 a major organization consisting primarily of workers under a democratic internal hierarchy governed by the principle of democratic centralism, who considered themselves the leaders of the revolutionary working class of Russia. Their beliefs and practices were often referred to as Bolshevism.