Radical political change may be brought about by either violent or non-violent means, as distinct from coups d'Etat which may simply exchange one political leader or dictator for another or for a clique. Revolution may occur on the basis of class or race (as in decolonization). It may result in economic and ideological revolution and repression of the old order. The more violent the revolution, the more intense the ensuing repression is likely to be. Political revolution may cause social and economic disruption and adaptation problems, or resistance, counter revolution and civil war.
A civil war or other resort to violence by a country's citizens in order to change the government may be termed a revolution. From a political point of view, it is a revolution if the system itself is changed and not simply the officials (as often is the case in a "coup d'Etat").
In the twentieth century some revolutions that might be cited (excluding wars of independence) are those of the Communists in Russia, China, Yugoslavia and Cuba, and that of the Islamic fundamentalists in Iran. A number of others (for instance, Ethiopia) can be listed, mainly Communistic. There are also revolutionary movements whose motives are linguistic or ethnic - as the Basque and Quebecôis among others - or specifically racial.