Nanotechnology involves manipulating materials at the nanoscale to enhance their properties. In concrete, nanosilica and carbon nanotubes are used to improve strength and durability. Carbon nanotubes are cylindrical structures that can strengthen concrete. Nanosilica controls degradation and improves water resistance. Nanoparticles in paint provide insulation and corrosion protection. Nanoparticles in glass coatings sterilize surfaces and prevent fouling. Nanoparticles in wood and stone coatings protect from dirt and weathering while allowing surfaces to breathe. In steel, nanoparticles at grain boundaries increase corrosion and weld resistance.