Hannah Arendt (1906-1975) is one of the most important philosophers of the 20th century. She is author of many books such as The Human Condition (1958), Eichmann in Jerusalem: A Report on the Banality of Evil (1963), but her masterpiece is The Origins of Totalitarianism (1951).
In this last book, Arendt talks about three important topics: antisemitism (first section), imperialism (second section) and totalitarianism (third section).
According to Hannah Arendt, two examples of totalitarianism are Nazi Germany and Communist Russia. In both political systems, we find the key features of totalitarianism: the dissolution of social classes, massification, a charismatic leader, the use of terror to control society and, overall, a total absence of freedom.
In conclusion, totalitarianism is the destruction of the human condition. A danger that could arise at any time. For this reason, we always have to be careful.