It is a feeling of profound inadequacy that becomes the core, the center, of one's thoughts and feelings. Let's illustrate this. Think of our personhood as being a piece of fabric. Shame involves the entire fabric of the person. The urge is to hide and protect one's self from exposure.
Some women cut and burn themselves, some starve themselves as a form of self-punishment.
Some act obnoxious so others will reject them because they reject themselves. Many confuse this self-hatred with humility. It is not. All of this is self motivated. Shame by its very nature is always internalized.