Original: The SS, through its intelligence arm, the Security Service (Sicherheitsdienst, or SD), dealt with Jews, Gypsies, communists and those persons of any other cultural, racial, political or religious affiliation deemed by the Nazis to be either Untermensch (sub-human) or in opposition to the regime, and placing them in concentration camps.
Simplified: The SS, through its Security Service (Sicherheitsdienst, or SD), hunted down Jews, Gypsies, communists and any persons who the Nazis believed to be either Untermensch (sub-human) or against the regime.