Nazism ( NA(H)T-siz-əm), formally 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 in 1930s Europe, it was frequently referred to as Hitler Fascism (German: Hitlerfaschismus) and Hitlerism (German: Hitlerismus). The later related term "neo-Nazism" is applied to other far-right groups with similar ideas which formed after the Second World War when the Third Reich collapsed.

Nazism is a form of fascism, with disdain for liberal democracy and the parliamentary system. It incorporates a dictatorship, fervent antisemitism, anti-communism, anti-Slavism, anti-Romani sentiment, scientific racism, white supremacy, Nordicism, social Darwinism and the use of eugenics into its creed. Its extreme nationalism 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 strongly 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 an Aryan or Nordic 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 additional lands for German expansion under the doctrine of Lebensraum and exclude those whom they deemed either Community Aliens or "inferior" races (Untermenschen).