Marxism-Leninism is a communist ideological stream that emerged as the mainstream tendency amongst the Communist parties in the 1920s as it was adopted as the ideological foundation of the Communist International during Stalin's era.
However, in various contexts, different (and sometimes opposing) political groups have used the term "Marxism-Leninism" to describe the ideology that they claimed to be upholding.
Whether Stalin's practices actually followed the principles of Marx and Lenin is still a subject of debate amongst historians and political scientists. Trotskyists in particular believe that Stalinism contradicted authentic Marxism and Leninism, and they initially used the term "Bolshevik-Leninism" to describe their own ideology of anti-Stalinist (and later anti-Maoist) communism. Left communists rejected "Marxism-Leninism" as an anti-Marxist current.
The term Marxism-Leninism is most often used by those who believe that Lenin's legacy was successfully carried forward by Joseph Stalin (Stalinists). However, it is also used by some who repudiate Stalin, such as the supporters of Nikita Khrushchev.
After the Sino-Soviet split, communist parties of the Soviet Union and the People's Republic of China each claimed to be the sole intellectual heir to Marxism-Leninism. In China, they claim that Mao had "adapted Marxism-Leninism to Chinese conditions" evolved into the idea that he had updated it in a fundamental way applying to the world as a whole; consequently, the term "Marxism-Leninism-Mao Zedong Thought" (commonly known as Maoism) was increasingly used to describe the official Chinese state ideology as well as the ideological basis of parties around the world who sympathized with the Communist Party of China. Following the death of Mao, Peruvian Maoists associated with the Communist Party of Peru (Sendero Luminoso) subsequently coined the term Marxism-Leninism-Maoism, arguing that Maoism was a more advanced stage of Marxism.
Following the Sino-Albanian split, a small portion of Marxist-Leninists began to downplay or repudiate the role of Mao Zedong in the International Communist Movement in favor of the Party of Labor of Albania and a stricter adherence to Stalin.
In North Korea, Marxism-Leninism was officially superseded in 1977 by Juche, in which concepts of class and class struggle, in other words Marxism itself, play no significant role. However, the government is still sometimes referred to as Marxist-Leninist - or, more commonly, Stalinist - due to its political and economic structure (see History of North Korea).
In the other three "communist states" existing today - Cuba, Vietnam, and Laos - the ruling Parties hold Marxism-Leninism as their official ideology, although they give it different interpretations in terms of practical policy.
In party names, the appellation 'Marxist-Leninist' is normally used by a communist party who wishes to distinguish itself from some other (and presumably 'revisionist') communist party in the same country.
Popular confusion abounds concerning the complex terminology describing the various schools of Marxist-derived thought. The appellation 'Marxist-Leninist' is often used by those not familiar with communist ideology in any detail (e.g. many newspapers and other media) as a synonym for any kind of Marxism.