Discretionary Power- The Use and Abuse

Discretionary power- What is it? Let"s have the most simple definition, because just like Einstein once said, "If you can"t explain it simply, you don"t understand it at all." Discretionary power is something an individual is entitled to do, but does not have to do it. "Entitled" is not the right for it,though.
Discretionary Power- The Use and Abuse