Nanotechnology is defined by the National Nanotechnology Initiative as understanding and controlling matter at dimensions between approximately 1 and 100 nm, where unique phenomena enable novel applications. The method of application is usually site specific and is dependent on the type of geology and hydrogeology in the treatment zone and the form in which the nZVI is injected. Nanotechnology is of interest for environmental applications, such as contaminated site remediation, because of the large specific surface area of nanoscale materials, as a result of which their reactivity in chemical or biological surface-mediated reactions can be greatly enhanced in comparison with the same material at larger sizes. nZVI technology is an innovative technology for contaminated site remediation that has been demonstrated to be effective for a wide range of contaminants. The unique characteristics of nZVI, such as small particle size and large specific surface area, make it effective for fast reaction with contaminants, as shown in controlled laboratory experiments.