Nationalism may refer to either of two different but related concepts: an ideology concerned with the creation, maintenance, and/or defense of a nation-state; or an extreme version of this ideology, which results in the rejection of others who do not belong to the same nation. Both definitions have currency in political debates on topics such as democracy, independence, self-determination, migration, and xenophobia. This entry will explain both of these senses of nationalism, by defining nations and nation-states, illustrating [Page 527]nationalism as a psychologically influential ideology with specific reference to the importance of national identity content, and outlining individual differences in relating to national identity.