An attempt will be make to formulate the general theory of defects in mediums and to establish general laws of generating and healing of defects. We propose a kinematic description of mediums with defects, introduce definitions for defects of various kinds, present a classification of mediums with defects, and note that the theory of defects is of hierarchic structure. It is shown that defects of all the known kinds may be itemized according to the classification of defects proposed with ease. We reveal a wide class of new defects and present their interpretation. The fact of existence of new classes of defects may be directly related to known theoretical and experimental facts testifying the possibility of generation of dislocation defects and disclination defects.