The present paper reviews the application of nanotechnology in geotechnical engineering, in which the concept of nanotechnology as well as the new concept of nanosol is explained. We have also given explanation for nanometer additives used in the introduced soil, different forms of nanoparticles, their specific properties, and effects of these nanoparticles on engineering properties of soil including index properties and strength, and analyzed the reasons through which these effects are caused. Furthermore, influence of recent advances in nanoinstruments and electron microscopes as well as their application in geotechnical studies.