What is wisdom?

What exactly is wisdom and why would or should anyone strive to achieve it?  The significance is conveyed best through examining the deeper concepts of the "Serenity Prayer":

 

God grant me the serenity to accept the things I cannot change;

 

Relinquish your controlling nature to whatever higher (religious, universal, etc) power you believe in to accept the reality of the present conditions and circumstances - instead of fighting that reality with illusions of how things 'should' or 'should not' be.

Courage to change the things I can;

However, there's always the choice of making responsible decisions to take actions which we know are necessary, regardless of unknown outcomes or consequences. Our Life is determined by the decisions and actions that we take and the thoughts that we hold - by no other forces. We must in all cases live with the consequences of our decisions or our lack of decision. The only thing that we can change is our perspective as we view reality, learning to make wiser choices by better thinking each moment.

And wisdom to know the difference.

Wisdom is not how you think, but specific behavior [what you do] based on life's experiences: an acquired ability to remember and later recognize the things which do or do not coincide with reality; the things which are true and honest; the eventual success of numerous mistakes strung together; learning not to engage in more foolishness than what can be laughed at [instead of bringing tears].