Nazism ( NA(H)T-see-iz-əm), formally named National Socialism (NS; German: Nationalsozialismus, German: [natsi̯oˈnaːlzotsi̯aˌlɪsmʊs] ), is the far-right totalitarian socio-political ideology and practices associated with Adolf Hitler and the Nazi Party (NSDAP) in Germany. During Hitler's rise to power, it was frequently referred to as Hitler Fascism (German: Hitlerfaschismus) and Hitlerism (German: Hitlerismus). The term "neo-Nazism" is applied to other far-right groups with similar ideology, which formed after World War II, and after Nazi Germany collapsed.

Nazism is a form of fascism, with disdain for liberal democracy and the parliamentary system. Its beliefs include support for dictatorship, fervent antisemitism, anti-communism, anti-Slavism, anti-Romani sentiment, scientific racism, white supremacy, Nordicism, social Darwinism, homophobia, ableism, and the use of eugenics. The ultranationalism of the Nazis originated in pan-Germanism and the ethno-nationalist Völkisch movement which had been a prominent aspect of German ultranationalism since the late 19th century. Nazism was influenced by the Freikorps paramilitary groups that emerged after Germany's defeat in World War I, from which came the party's underlying "cult of violence". It subscribed to pseudo-scientific theories of a racial hierarchy, identifying ethnic Germans as part of what the Nazis regarded as a Nordic Aryan master race. Nazism sought to overcome social divisions and create a homogeneous German society based on racial purity which represented a people's community (Volksgemeinschaft). The Nazis aimed to unite all Germans living in historically German territory, as well as gain lands for German expansion under the doctrine of Lebensraum and exclude those they deemed either Community Aliens or "inferior" races (Untermenschen).