Metallic glasses (MGs) are metallic materials without long-range ordering structures, which endows them with unique properties such as ultrahigh strength and hardness, high wear and corrosion resistances. MGs can be plastically thermoformed like plastics because their viscosity drops with the increase of temperature in their supercooled liquid region (SLR), which is a temperature interval localized between glass transition temperature Tg and crystallization temperature Tx. MGs display good plasticity in the case of high temperature combined with low strain rate. In contrast, when the temperature is under the glass transition temperature (Tg), the deformation is localized into shear bands and fracture occurs immediately after the initiation of shear bands. The material shows an asymmetry between tension and compression. Shear-banding is a plastic-deformation mode in all materials. Particularly, shear-banding is a form of plastic instability that localizes large shear strains in a relatively thin band when a material is deformed. This shear banding behavior of bulk metallic glasses (BMGs) is usually a weakness for these materials but sometimes may be transformed in an advantage by using good engineering solutions. A well known engineering application is the kinetic energy penetrator (KEP), when is used the effect of “self-sharpening” penetration. Shear bands are of crucial importance for deformation behavior of (MGs). Controlling the shear-banding is quite equivalent with the controlling of plasticity and failure at room temperature. This work provides an up-to-date overview on the fundamentals of shear-banding in (MGs) and also of the progress achieved very recently on this subject.