Main types of crystal structures with different atomic Main types of crystal structures with different atomic defects (point, volume, planar and linear) are considered using defects (point, volume, planar and linear) are considered using inorganic compounds as an example. The review presents the inorganic compounds as an example. The review presents the results of composite analysis of such real structures. Their results of composite analysis of such real structures. Their symmetry, ordering, ways of description, nomenclature and the symmetry, ordering, ways of description, nomenclature and the possibility of the diagnostics from diffraction patterns are dis-possibility of the diagnostics from diffraction patterns are discussed. The results of studies provide evidence that polymorphism cussed. The results of studies provide evidence that polymorphism is typical of real crystal structures. The bibliography includes 101 is typical of real crystal structures. The bibliography includes 101 references references. .