Based on the study of NACE International, the global cost of corrosion is estimated to be US2.5 trillion in 2016. As reported, implementing corrosion prevention best practices could save 15�35 of this global cost of damage. In general, metals can be protected by various conventional methods, such as protective coatings, corrosion inhibitors, electrochemical methods (anodic and cathodic protections), and metallurgical design. Recently, nanotechnology can offer the new routes to protect metal effectively at the nanoscale for early stage. This chapter aims to explain how metals can be protected at the nanoscale. It covers the new techniques using nanoalloys, nanoinhibitors, nanocoatings, nanogenerators, nanosensors, and photogenerated cathodic protection. © 2020 Elsevier Inc. All rights reserved.