 Although not observable in brittle materials (for instance glass at room temperature), shear bands or, more generally, ‘localized deformations’ usually develop within a broad range of ductile materials (alloys, metals, granular materials, plastics, polymers, and soils) and even in quasi-brittle materials (concrete, ice, rock, and some ceramics).The relevance of the shear banding phenomena is that they precede failure, since extreme deformations occurring within shear bands lead to intense damage and fracture.Therefore, the formation of shear bands is the key to the understanding of failure in ductile materials, a research topic of great importance for the design of new materials and for the exploiting of existing materials in extreme conditions.