What was the original purpose of the SS as noted in the biography, Adolf Hitler?

The SS begins as Hitler's personal bodyguard. Hitler uses the SS as a personal bodyguard and as a defense and control against the initially larger and more powerful SA. Later, it is vastly expanded and acquires new powers when the SA is partially suppressed in July 1934. There are army units that only fight in military combat under the SS. The SS also includes parts of the Secret Police, the Gestapo. and units such as execution squads and concentration camp guards.