SS is an abbreviation for Schutzstaffel, or Defense Echelon.  The SS was the black-uniformed elite police of the Nazi Party of Germany, regarded by its commander Heinrich Himmler as an imperial guard.  The SS was organized into military units, and trained separately from the German Army.  Initially, the SS was responsible for the personal security of Adolf Hitler, but its role expanded to include all police and racial matters in Germany and German-held territories.  In that capacity, members of the SS organized and implemented the Final Solution.  After the war, the organization was declared illegal by the Nuremberg International Military Tribunal, and its leaders were tried at the Nuremberg Trials.