A thorough and critical review on Shear Thickening Fluids (STFs) is presented based on a literature survey. The rheological properties of STFs are discussed considering many factors affecting shear thickening behavior and the use of STFs in protective systems is reviewed. The main focus of this review is multi-phase STFs, relatively new to the literature (in the last five years). Multi-phase STFs include a second phase in suspensions and the influences of this additional phase on rheological behavior and protective applications are discussed extensively. Based on this extended review, STF do benefit protective applications, but the major contribution is not driven by the shear thickening behavior. Rather, STFs are responsible for the increase in friction along fabrics and enhanced fiber/yarn coupling in fabric based protective systems. As a result, of these effects, the load transfer is spread over a wider area and penetration depth is lowered in an impacted structure.