Nazism or Naziism, a form of National Socialism (German: Nationalsozialismus), refers primarily to the totalitarian ideology and practices of the Nazi Party (National Socialist German Workers' Party, German: Nationalsozialistische Deutsche Arbeiterpartei or NSDAP) under Adolf Hitler. It also refers to the policies adopted by the government of Germany from 1933 to 1945, a period in German history known as Nazi Germany or the "Third Reich".
On January 5, 1919, the party was founded as the German Workers' Party (DAP) by Anton Drexler. Hitler, a corporal, was sent to investigate the party by German intelligence and was invited to join after impressing them with his speaking ability after getting into an argument with party members. Hitler later accepted the invitation and joined the party in September 1919, and he became propaganda boss. The party was renamed the National Socialist German Workers' Party on April 1, 1920, against Hitler's choice of Social Revolutionary Party. Hitler became the party leader on July 29, 1921.
Nazism was not a precise, theoretically grounded ideology, or a monolithic movement, but rather a (mainly German) combination of various ideologies and groups, centered around anger at the Treaty of Versailles and what was considered to have been a Jewish/Communist conspiracy to humiliate Germany at the end of the First World War. It therefore consisted of a loose collection of positions focused on those held to blame for Germany's defeat and weakness: anti-parliamentarism, ethnic nationalism, racism, collectivism, eugenics, antisemitism, opposition to economic and political liberalism, a racially-defined and conspiratorial view of finance capitalism, and anti-communism. As Nazism became dominant in Germany, especially after 1933, it was defined in practice as whatever was decreed by the Nazi Party and in particular by the Führer, Adolf Hitler.