The concept of inner child speaks about an internal aspect of us that is childlike or from our childhood and which carries qualities or the result of experiences from that period of time.  Our inner children hold feelings, emotions and beliefs that can still influence us in our lives as adults in ways which can seem to be to our benefit or detriment.  If you are struggling with extreme beliefs such as feeling not good enough or believe yourself to be unworthy, it is likely these are held by your inner child.  Similarly if you hold extreme emotions such as rage or shame, it is likely that these are being held by an inner child part.