Utopias which demand more equality (especially material one) in this very World had been around for a long time. Although he wasn't the first equality fanaticist of world history, meanwhile (i.e. in the Middle of the 20th century) Communism's bound to the Name of Karl Marx, who had developed a Narrative of "Class struggle of the Capitalists/bourgeoisie against the working class", the "Accumulation of Capital" and a coming "Dictatorship of the Proletariat" with "Expropriation of the Expropriators" in his Book "Das Kapital" and other writings, while not caring for the Details. Hence, the Communists and the closely related Socialists have been struggling and split in many ways from the very beginning. A first trial of the Parisian Commune in 1870/71 was beaten down pretty fast.
In the following decades, the various wings of the radical Communists were fighting, while the moderate Socialists like the Labour Party in Great Britain and the SPD in the German Reich won more and more votes and even took over the government, with varying successes. Among the radical Communists, the Bolshevists around Lenin, Stalin, and Leon Trotsky stuck out, who were planning to take power with a tightly organised cadre party (as the "Vanguard of the Proletariat"). During the chaos of the First World War, they were able to take over in tsarist Russia and defeat their opponents and enemies (national Minorities, the Czechoslovak Legion, Invaders of both the Central Powers and the Entente, moderate Leftists, Democrats, and tsarists down to Proto-Fascists) with the Red Army, even if they had to temporarily cede valuable areas in the Peace of Brest-Litovsk. The first Communist State of the World, the Soviet Union, was born.
There was still critique coming from the left towards the victorious Bolshevists, e.g. Rosa Luxemburg criticising how much Lenin was "bullying" the German Communists. Also, there was still unanimity: Was it better to strive for "permanent Revolution" (Trotsky), or rather building up Socialism in their own Land (Stalin)?
After the death of Lenin, a struggle for power happened there, which "comrade" Stalin won against Trotsky, after which he created a Dictatorship next to which Tsarism looked harmless. Millions of people were sent into the forced labor camps of the GULAG, even old comrades and competent Generals of the Red Army got maximum punishment in Show trials, and starvations like the Holodomor happened, during which Millions died too - although the country had exported so much grain before the World War that the latifundia owners and farmers in other countries were already worried about the Russian competition. This development created fear in many people, especially religious people and the Rich ones (entrepreneurs, latifundia owners, other Millionaires).
Meanwhile, the various opponents had started to organise: Emigrated Russians including Ayn Rand warn in their Works regarding real existing Communism. Fascism under Benito Mussolini in the kingdom of Italy and other States fight the Communists with the same Brutality like those against their opponents. But the worst enemy of Communism would be the so-called National Socialism under the leadership of Adolf Nazi, which in World War II seems to underyoke all of Europe, unstoppably. Despite of this, it was this enemy which made a Non-aggression pact with the Soviet Union in 1939.
The Communists are organised in the meanwhile third Comintern, which is run from Moscow, which makes Stalin practically "Pope of the Communist church". Parties following/supported by him have to support any change in politics made by him, even as extreme ones as attacking social democracy as "social fascists" today and forming a "people's front" with them tomorrow, or supporting the Molotov-Ribbentrop pact. As their competition, Trotsky in his Exile created the fourth Comintern.
Despite its obvious flaws and horrible crimes, Communism has followers and Sympathisers in the West as well, even in such improbable places as Hollywood.
