The most common misconception over the understanding of 'forgiveness' is that someone is being 'let off the hook' when they are forgiven. In fact they have not been let off but have to live with what they have done or said, that is of course assuming they have a conscience.
There can be however a 'letting off the hook' for the one who forgives! If someone offends you in any way, you can deal with it in many ways such as revenge, spreading gossip about them, giving them a hard time each time you see them etc etc, which in fact allows them still to have a hold over you and your feelings. The alternative is to forgive.. or to give away any feelings of anger, resentment, need for revenge, pain, in favour of not letting those feelings have any hold over you or your emotions. In other words if you are unforgiving of a perpetrator, they still have a hold over you and your emotions. If you forgive, they can no longer have that hold because you have shed any resentment or anger