A communist party is a political party that advocates the application of the social and economic principles of communism through state policy. The name originates from the 1848 tract Manifesto of the Communist Party by Karl Marx and Friedrich Engels. According to leninism, a Communist party is the vanguard party of the working class (proletariat), whether ruling or non-ruling, but when such a party is in power in a specific country, the party is said to be the highest authority of the dictatorship of the proletariat. Vladimir Lenin's theories on the role of a Communist party were developed as the early 20th-century Russian social democracy divided into Bolshevik (meaning "of the majority") and Menshevik (meaning "of the minority") factions. Lenin, leader of the Bolsheviks, argued that a revolutionary party should be a small vanguard party with a centralized political command and a strict cadre policy; the Menshevik faction, however, argued that the party should be a broad-based mass movement. The Bolshevik party, which eventually became the Communist Party of the Soviet Union, took power in Russia after the October Revolution in 1917. With the creation of the Communist International, the Leninist concept of party building was copied by emerging Communist parties worldwide.
The Chinese Communist Party is the world's largest political party, claiming nearly 78 million members at the end of 2009 which constitutes about 5.6% of the total population of mainland China.