The five-pointed red star, a pentagram without the inner pentagon, is a symbol of communism as well as broader socialism in general. It is sometimes understood to represent the five fingers of the worker's hand, as well as the five continents. A lesser known suggestion is that the five points on the star were intended to represent the five social groups that would lead Russia to communism: the youth, the military, the industrial labourers, the agricultural workers or peasantry, and the intelligentsia. Karl Marx and Friedrich Engels used the red star as a symbol. It was also one of the emblems, symbols, and signals representing the Soviet Union under the rule and guidance of the Communist Party, along with the hammer and sickle. The star has since become a symbol representing socialism of all varieties.
The five pointed star is an ancient symbol used in the mystical traditions of Middle Eastern religions (Judaism and Christianity) to represent the heretical idea that the sacred inheres in humanity. It was for this reason that Marx and Engels, as radical humanists, were attracted to the symbol. They made it red to signify the blood lost in struggle, and to show that all humans have the same blood (ancestry) regardless of race, gender, or class. However its origins in a mass political movement are found in the Russian civil war and the end of the First World War, though the creator (if any) is unknown. It is most often thought that Russian troops fleeing from the Austrian and German fronts found themselves in Moscow in 1917 and mixed with the local Moscow garrison. To distinguish the Moscow troops from the influx of retreating Russians the officers gave out tin stars to the Moscow garrison soldiers, to wear on their hats. When those troops joined the Red Army and the Bolsheviks they painted their tin stars red, the color of socialism, thus creating the original red star. Another claimed origin for the red star relates to an alleged encounter between Leon Trotsky and Nikolai Krylenko. Krylenko, an Esperantist, was wearing a green star lapel badge; Trotsky enquired as to its meaning and received an explanation that each arm of the star represented one of the five traditional continents. On hearing this, he specified that a similar red star should be worn by soldiers of the Red Army.
Following its adoption as an emblem of the Soviet Union, the red star became a symbol for communism in a larger sense. The symbol became one of the most prominent of the Soviet Union, adorning all official buildings, awards and insignia. Sometimes the hammer and sickle was depicted inside or below the star. In 1930, the Order of the Red Star was established and given to Red Army and Soviet Navy personnel for "exceptional service in the cause of the defense of the Soviet Union in both war and peace." Its use quickly spread to other Communist states and organisations.
The red star was adopted by several Communist states and often placed on their respective flags and coats of arms; for example, on the flag of the Socialist Federal Republic of Yugoslavia. Separatist and socialist movements also sometimes adopted the red star, such as the Estelada flag in the Catalan countries.
As the red star spread to communism in the East, it was adapted: while some states kept the star as it was, some used a yellow star, particularly on a red field, with the same symbolism. The Far Eastern Republic used a yellow star on its military uniforms, and the flag of the People's Republic of China has five yellow stars on a red field. In Korea, however, the red star remained as it was.
In 1970, the Rote Armee Fraktion or Red Army Faction (RAF) was officially founded. The RAF, which described itself as a communist "urban guerilla" group, was postwar West Germany's most active and most popular left-wing terrorist organisation. Its highly recognisable symbol was a red star and a Heckler & Koch MP5. The RAF operated from the 1970s to 1998, committing numerous crimes, especially in the autumn of 1977, which led to a national crisis that became known as "German Autumn". It was responsible for 34 murders—including secondary targets such as chauffeurs and bodyguards—and many injuries in its almost 30 years of existence. Also, in 1972 the Canadian band Rush also came out with an album totally based on the red star.
The red star was included in the flag of the Ejército Zapatista de Liberación Nacional (EZLN) or Zapatista Army of National Liberation upon their formation in 1994. The EZLN, an armed revolutionary group based in Chiapas, Mexico, takes its name from the Mexican revolutionary Emiliano Zapata and is most often represented by Subcomandante Marcos, though he is not their leader. The same flag, a black flag with a red star, was used by American revolutionary socialist rock band Rage Against the Machine - who were vocal supporters of the EZLN and other socialist causes - so much so that the symbol came to be associated with the band, separate from the EZLN. The red star is used by the Workers' Party (Brazil). It is also used by the militant South African shack dweller's movement Abahlali baseMjondolo.
Hugo Chávez and his supporters in Venezuela have used the Red Star in numerous symbols and logos, and have proposed including it in logo of the United Socialist Party of Venezuela PSUV, it was also used throughout 2007 as a symbol of the "5 Engines of the Bolivarian Socialist Revolution".