The Holocaust was the systematic persecution and murder of approximately 6 million Jews by the Nazi regime from 1933 to 1945. By 1945, two-thirds of European Jews had been killed. Jews were targeted by the Nazis due to long-standing anti-Semitism and Nazi beliefs about Aryan racial supremacy. The Nazis used concentration camps and death camps to carry out mass killings of Jews and other groups deemed "undesirable", with Auschwitz being the largest such camp where thousands died daily. After the war, the Nuremberg trials held Nazi leaders accountable for their war crimes and genocide.