This publication is aimed at formalization of the notions of «seismic zone» and «seismic belt». A seismic zone (SZ) is a territory defined and contoured in a technically active area. Within the limits of this territory, more than 10 seismic event with М>3 (К>9) occurred in the specified period of time (typically, 50 years), or the number of seismic event is not below a certain statistically relevant value. The external contour of SZ should be drawn according to the isolines of the corresponding density of registered earthquakes with М≥3, pending no less than three events within the given square area. In each case, selection of contours of SZ should be determined so that it can provide for classification of SZs. SZ should correspond to one or several tectonic structures. The interior structure of SZ can be zoned according to densities of earthquake epicentres.A seismic belt (SB) is a structure with a uniform geodynamic regime, wherein seismic zones are closely spaced. Typi cally, such structures are margins of plates or large intraplate blocks. In real time, SB is generally characterized by a perma nent state of lithospheric stresses. Stress vectors in local segments of SB may differ from the dominant type of stresses. They can be variable due to changes in strike of local and regional faults which control seismicity and also due to various direc tions of zones of the recent lithospheric destruction.The Earth's SBs and SZs are mapped. SBs and a number of most important SZs are briefly described. Main parameters of SBs and SZs are tabulated. Based on the available data on SBs and SZs and taking into account the common geodynamical settings and elongated localities of earthquake foci, we suggest that it is required to evaluate structural factors controlling the seismic process and its components (locations of earthquake foci) at all the hierarchic levels, i.e. seismic belts, seismic zones, fault zones wherein stresses are concentrated, and structures wherein earthquake foci are located.Due to differences in the structural factors of control and scaling of SB and SZ manifestation, criteria for occurrence of earthquakes of various magnitudes are significantly different. Rare catastrophic earthquakes in SB result from the evolution of interplate and large interblock margins in the geochronological scale intervals and/or disturbances of the evolution regu larities due to catastrophic seismic event in the adjacent SB. Developing tectonophysical models of SBs is a future challenge.In SZ, earthquakes of medium magnitudes and rare strong seismic events results from the impact of strain waves on the megastable state of the recent lithospheric destruction zones which comprise the SZ structure. Time spans between seismic events in SZ are estimated in real time scales (decades, years, months) and thus can be considered instant in relation to peri ods of the geological evolution of interplate margins and other large structural margins (hundred thousand years, million years). In terms of the given time evaluation, the ...