2nd Congress of the Russian Social Democratic Labour Party in the context of "Bolsheviks"

The Bolsheviks, led by Vladimir Lenin, were a radical faction of the Marxist Russian Social Democratic Labour Party (RSDLP) which split with the Mensheviks at the Second Party Congress in 1903. The Bolshevik party, formally established in 1912, seized power in Russia in the October Revolution of 1917 and was later renamed the Russian Communist Party, All-Union Communist Party, and ultimately the Communist Party of the Soviet Union. Its ideology, based on Leninist and later Marxist–Leninist principles, became known as Bolshevism.

The origin of the RSDLP split was Lenin's support for a smaller party of professional revolutionaries, as opposed to the Menshevik desire for a broad party membership. The influence of the factions fluctuated in the years up to 1912, when the RSDLP formally split in two. The political philosophy of the Bolsheviks was based on the Leninist principles of vanguardism and democratic centralism. Lenin was also more willing to use illegal means such as robbery to fund the party's activities. By 1917, influenced by the experiences of World War I, he reached the conclusion that the chain of world capitalism could "break at its weakest link" in Russia before it assumed the level of the advanced countries, opposing theorists such as Georgi Plekhanov. Lenin had also come to view poorer peasants as potential allies of the relatively small Russian proletariat.

The Mensheviks (lit. 'the Minority') were a faction of the Marxist Russian Social Democratic Labour Party (RSDLP) which split with Vladimir Lenin's Bolshevik faction at the Second Party Congress in 1903. Mensheviks held more moderate and reformist views as compared to the Bolsheviks, and were led by figures including Julius Martov and Pavel Axelrod.

The initial point of disagreement was the Mensheviks' support for a broad party membership, as opposed to Lenin's support for a smaller party of professional revolutionaries. The Bolsheviks gained a majority on the Central Committee in 1903, although the power of the two factions fluctuated in the following years. Mensheviks were associated with Georgi Plekhanov's position that a bourgeois-democratic revolution and period of capitalism would need to occur before the conditions for a socialist revolution emerged. Some Mensheviks, notably Alexander Potresov, called for the party to suspend illegal revolutionary work to focus more on trade union work (legal since 1906) and elections to the Duma; this was condemned by Lenin.

The Russian Social Democratic Labour Party (RSDLP), also known as the Russian Social Democratic Workers' Party (RSDWP) or the Russian Social Democratic Party (RSDP), was a socialist political party founded in 1898 in Minsk, Russian Empire. The party emerged from the merger of various Marxist groups operating under Tsarist repression, and was dedicated to the overthrow of the autocracy and the establishment of a socialist state based on the revolutionary leadership of the Russian proletariat.

The RSDLP's formative years were marked by ideological and strategic disputes culminating at its Second Congress in 1903, where the party split into two main factions: the Bolsheviks, led by Vladimir Lenin, who advocated a tightly organized vanguard of professional revolutionaries; and the Mensheviks, led by Julius Martov and others, who favored a more moderate, broad-based model. During and in the years after the 1905 Revolution, the RSDLP operated both legally and underground, publishing newspapers, infiltrating trade unions, and agitating among industrial workers.

Georgi Valentinovich Plekhanov (Russian: Георгий Валентинович Плеханов [ɡʲɪˈorɡʲɪj vəlʲɪnʲˈtʲinəvʲɪtɕ plʲɪˈxanəf] ; 11 December [O.S. 29 November] 1856 – 30 May 1918) was a Russian Marxist theorist, philosopher, and revolutionary. After beginning his revolutionary career as a populist, in 1883 Plekhanov established the Emancipation of Labour group, the first Russian Marxist political organisation. He is widely regarded as the "father of Russian Marxism", and his theoretical works were instrumental in converting a generation of revolutionaries, including Vladimir Lenin, to the cause.

Plekhanov was a prominent leader in the Russian Social Democratic Labour Party (RSDLP) and the Second International. In 1900, he collaborated with Lenin in founding the party newspaper Iskra, and at the party's Second Congress in 1903, initially sided with Lenin's Bolshevik faction. However, he soon broke with the Bolsheviks over their organisational principles, which he criticised as overly centralist, and became a leading figure in the opposing Menshevik faction. During the 1905 Russian Revolution, Plekhanov maintained that Russia was only ready for a bourgeois-democratic revolution and argued against what he saw as premature attempts to seize power by the proletariat.

The Old Bolsheviks (Russian: ста́рый большеви́к, romanized: stary bolshevik), also called the Old Bolshevik Guard or Old Party Guard, were members of the Bolshevik faction of the Russian Social Democratic Labour Party prior to the October Revolution of 1917. Many Old Bolsheviks became leading politicians and bureaucrats in the Soviet Union and the ruling Communist Party. While some died over the years from natural causes, many were removed from power, imprisoned in gulags or executed by the late 1930s, as a result of the Great Purge by Joseph Stalin.

Yuliy Osipovich Tsederbaum (Russian: Юлий Осипович Цедербаум [ˈjʉlʲɪj ˈosʲɪpəvʲɪtɕ tsɨdʲɪrˈbaʊm]; 24 November 1873 – 4 April 1923), better known as Julius Martov (Юлий Мартов [ˈmartəf] ), was a Russian revolutionary and a leader of the Mensheviks, the minority faction of the Russian Social Democratic Labour Party (RSDLP). A close friend and collaborator of Vladimir Lenin in the early years of their revolutionary careers, he became his chief rival after the RSDLP split at its Second Congress in 1903.

Born into a middle-class, assimilated Jewish family in Constantinople, Martov became a Marxist activist in the Russian Empire in the early 1890s. With Lenin, he co-founded the League of Struggle for the Emancipation of the Working Class in 1895. Both were arrested shortly after and exiled to Siberia. After his exile, Martov joined Lenin and Georgy Plekhanov in founding the party newspaper Iskra, which became the primary organ of the RSDLP. At the Second Party Congress, Martov's proposal for the definition of party membership, which was broader and more inclusive than Lenin's, was passed. However, after several delegates walked out, Lenin's faction won a vote on the composition of the party's Central Committee, leading to the historic split between Lenin's Bolsheviks ("majority-ites") and Martov's Mensheviks ("minority-ites").