Nationalism, in its broadest sense, is a devotion to one's own nation and its interests over those of all other nations. The term can also refer to a doctrine or political movement that holds that a nation — usually defined in terms of ethnicity or culture — has the right to constitute an independent or autonomous political community based on a shared history and common destiny. For nationalists, the borders of the state should be congruent with the borders of the nation. Extreme forms of nationalism, such as those propagated by fascist movements in the twentieth century, hold that nationality is the most important aspect of one's identity and attempt to define the nation in terms of race or genetics.
Nationalism has had an enormous influence on world history. In modern times, the nation-state has become the dominant form of societal organization. Historians use the term nationalism to refer to this historical transition and to the emergence and predominance of nationalist ideology.
Patriotism need not necessarily pave the way for people to hate each other in the name of their respect to their nation. Nations are mere administrative divisions and should learn to co-exist in a peaceful world.