Hatred of Jews. The word itself is a corruption of the true meaning, engineered by Hitler. "Semites" are not Jews, but rather "semitic" refers to a language grouping including Hebrew, Arabic, Egyptian, Phoenician, Babylonian, and Assyrian. Hitler, however, did not include anti-Arabic beliefs in his doctine, and therefore redefined the word to mean Anti-Judaism. For this reason, we choose not to use the term "anti-Semitism," though it is also an accepted spelling.
"Special Duty Groups" - Einsatzgruppen were mobile death squads, which executed innocent Jewish civilians after the subjugation of rural villages. Before the death camps, the Nazis used these groups to exact their "Final Solution to the Jewish Problem."
"Mercy Killing." Hitler initiated these programs to execute individuals who were handicapped physically or mentally, calling them "impure Aryans." In doing so, he sought to keep the "Aryan nation" pure. The Euthanasia program was also a tool for research into extermination techniques, and the results of the experiments directed the creation of the death camps.
Led by Hitler's once-close friend, Ernst Rohm, the SA were Hitler's first army. The largely untrained army fell apart after the "Night of the Long Knives," during which Hitler ordered the executions of SA officials, including Ernst Rohm himself.