Russian Social Democratic Labour Party

Bolsheviks: This term refers to a faction of the Russian Social Democratic Labor Party; they were radical revolutionaries who supported a small number of committed 'professional' revolutionaries. They eventually became leaders of Russia after October Revolution.

Mensheviks: This term refers to another faction within the same party; they believed in more gradual change and wanted a broad base of popular support for socialism.

October Revolution: This was an event that took place in Russia during World War I, where power was seized from Provisional Government by armed Bolshevik workers known as Red Guards.