quality:corruption, linguistic:voice_change
Nationalism is an idea or movement that holds that the nation should be congruent with the state. As a movement, it presupposes the existence and tends to promote the interests of a particular nation, especially with the aim of gaining and maintaining its sovereignty (self-governance) over its perceived homeland to create a nation-state. It holds that each nation should govern itself, free from outside interference (self-determination), that a nation is a natural and ideal basis for a polity, and that the nation is the only rightful source of political power. It further aims to build and maintain a single national identity, based on a combination of shared social characteristics such as culture, ethnicity, geographic location, language, politics (or the government), religion, traditions and belief in a shared singular history, and to promote national unity or solidarity. There are various definitions of a "nation", which leads to different types of nationalism. The two main divergent forms are ethnic nationalism and civic nationalism.

Beginning in the late 18th century, particularly with the French Revolution and the spread of the principle of popular sovereignty or self determination, the idea that "the people" should rule is developed by political theorists. Three main theories have been used to explain the emergence of nationalism:

The moral value of nationalism, the relationship between nationalism and patriotism, and the compatibility of nationalism and cosmopolitanism are all subjects of philosophical debate. Nationalism can be combined with diverse political goals and ideologies such as conservatism (national conservatism and right-wing populism) or socialism (left-wing nationalism). In practice, nationalism is seen as positive or negative depending on its ideology and outcomes. Nationalism has been a feature of movements for freedom and justice, has been associated with cultural revivals, and encourages pride in national achievements. It has also been used to legitimize racial, ethnic, and religious divisions, suppress or attack minorities, undermine human rights and democratic traditions, and start wars, being frequently cited as a cause of both World Wars.