Adolf Hitler was employed by the German Army in Munich to investigate small political parties. Whilst observing the DAP, Hitler became involved in meetings and soon became an active member. The party was renamed the National Socialist German Workers Party (Nazionalsozialistische Deutsche Arbeiterpartei – NSDAP or ‘Nazi’ for short.)
By 1921 Hitler became leader of the party (Führer). He was a powerful political speaker. By appealing to all their fears and discontents Hitler began persuading unemployed people and disaffected war-veterans that the Jews and communists were responsible for all the problems in Germany. By November 1921 the Nazis had 3,000 members with Hitler as Führer.
Source: Visit the Holocaust Explained Website