Marxism-Leninism (also known as Bolshevism) is a communist political philosophy developed by Vladimir Lenin based on the beliefs of Karl Marx. It guided the Bolsheviks and became the official ideology of the Soviet Union following the Russian Revolution in the 1920s. After World War Two it became official also in Soviet satellite states like East Germany, Poland, Czechoslovakia and Hungary, as well as the countries of China, Cuba, Vietnam, and Laos where it remains dominant in the 21st century.
It stated that a global revolution was not needed to establish socialism; the concept of "Socialism in One Country" was supported. Marxism-Leninism instead advocated supporting revolutionary groups across the world, overseeing a slow transition from capitalism to socialism, and in theory establishing democratic centralism ("diversity in discussion, unity in action"), while in practice building single party states, often described as totalitarian.
Variants of Marxism-Leninism include Stalinism, Trotskyism and Maoism.