I believe there are two levels of forgiveness. First one, the "surface forgiveness", when you simply tell a person that you forgive him/her. This act itself may feel liberating, but at the same time it could only remain among those words that have been spoken without having any deeper effect.
Another level of forgiveness, in my opinion, is way deeper and way more difficult to reach. It basically requires you to dive deep inside your inner world and find out about a part of yourself that was hurt by a person. It may or may not turn out to be a case of some hurtful personal belief about yourself being triggered by another person's behavior. When realization like this occurs, it might as well be clear that there's nobody to forgive - it was all just an internal issue that required your attention to be solved. This is what I'd call a true forgiveness.