Although fault damage zones have widely been used for fault analyses and applications associated with fluid flow and foundation safety, they were not clearly defined and classified. Thus, there are some problems related with statistical analysis of fault damage zones showing data scattering. We believe that one of the fundamental reasons for these problems comes from subjective definitions of the term ‘damage zone’. Thus, we re-classified damage zones into along-fault, around-tip and cross-fault damage zones based on descriptive views of an arbitrary fault exposure as well as their tridimensional locations around a segmented fault system. We also proposed an advanced field technique to more accurately define a damage zone boundary across-fault using the distribution of cumulative fracture frequency. This method can be applicable to borehole data as well as field data based on the change of slope gradients of the cumulative distribution of deformation structures. We argue that this damage zone classification and definition could be adopted and used to prevent discrepancies in fault damage zone data. This will help us to gain a better understanding of fault damage zone properties and their scaling relationships.