Communist, revolutionary-socialist, and syndicalist delegates met in Moscow to establish the Communist International.

Communism is a radical left or far-left sociopolitical, philosophical, and economic ideology within the socialist movement, whose goal is the creation of a communist society, a socioeconomic order centered on common ownership of the means of production, distribution, and exchange that allocates products in society based on need. A communist society entails the absence of private property and social classes, and ultimately money and the state.

Revolutionary socialism is a political philosophy, doctrine, and tradition within socialism that stresses the idea that a social revolution is necessary to bring about structural changes in society. More specifically, it is the view that revolution is a necessary precondition for transitioning from a capitalist to a socialist mode of production. Revolution is not necessarily defined as a violent insurrection; it is defined as a seizure of political power by mass movements of the working class so that the state is directly controlled or abolished by the working class as opposed to the capitalist class and its interests.

Syndicalism is a labor movement within society that, through industrial unionism, seeks to unionize workers according to industry and advance their demands through strikes and other forms of direct action, with the eventual goal of gaining control over the means of production and the economy at large through social ownership.

The 1st Congress of the Communist International was an international gathering of communist, revolutionary socialist, and syndicalist delegates held in Moscow which established the Communist International (Comintern). The gathering, held from March 2 to 6, 1919, was attended by 51 representatives of more than two dozen countries from around Europe, North America, and Asia.