Nationalism is an ideology and movement characterized by the promotion of the interests of a particular nation, especially with the aim of gaining and maintaining the nation's sovereignty (self-governance) over its homeland. Nationalism 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 (popular sovereignty). It further aims to build and maintain a single national identity—based on shared social characteristics such as culture, language, religion, politics, and belief in a shared singular history [page needed]—and to promote national unity or solidarity. Nationalism, therefore, seeks to preserve and foster a nation's traditional culture, and cultural revivals have been associated with nationalist movements. It also encourages pride in national achievements, and is closely linked to patriotism. [page needed] Nationalism is often combined with other ideologies, such as conservatism (national conservatism) or socialism (socialist nationalism) for example.