The Holocaust was the systematic mass murder of 6 million Jews by the Nazi regime during World War 2. Hitler outlined his plan for the genocide of Jews in his book Mein Kampf. In 1935, the Nazi government passed the Nuremberg Laws which stripped German Jews of their citizenship and banned marriage between Jews and non-Jews. Kristallnacht in 1938 saw the destruction of Jewish homes and businesses by Nazi forces and the arrest of 20,000 wealthy Jews. Concentration and extermination camps like Auschwitz and Buchenwald were established where many Jews and political prisoners died from brutal conditions or gas chambers.