Forgiveness

What is forgiveness?  It's assumed to be a common-sense term, but I've had trouble grasping it.  Given its centrality as a concept in my religion, I had better get some idea of it, I suppose.

Here’s WLC:  The philosophical literature typically treats forgiveness as a subjective change of attitude on the part of the person wronged, a determination to put away feelings of resentment, bitterness, or anger, a relinquishing of the desire for revenge. 

Forgiveness understood in this way does not preclude a retributive view of justice. One can personally forgive someone and still have the legal system demand satisfaction from them.