Define Nationalism.

Hint: Identification with one's own nation and support for its interests, especially to the exclusion or detriment of the interests of other nations.

Complete answer:
Nationalism is an ideology and movement that promotes a particular nation's interests (as in a community of people), especially to obtain and preserve the sovereignty of the nation (self-governance) over its homeland. Nationalism is a modern movement.

People have been attached to their native soul, to their traditions of history, and to establish territorial authorities throughout history. But it was not until the end of the 18th century that the general acceptance of nationalism began. It began to influence public and private life. It is the single determining factors of Modern history. Nationalism claims that each nation should govern itself, free from outside interference.

A nation is a natural and the ideal basis for a political system and that the nation is the only valid source of political power (popular sovereignty). It also seeks to build and retain a single national identity, based on the mutual social characteristics of culture, ethnicity, geographical place, language, politics (or government), faith, traditions, and belief in a single shared history, and to foster national unity or solidarity.

Nationalism aims to maintain and promote the traditional cultures of a country and nationalist movements have been associated with cultural revivals. It also promotes pride in national accomplishments and is closely related to patriotism.

Note: It is a structure built by individuals who think that their nation is superior to all others. Very frequently, this sense of superiority has its roots in a shared ethnicity.