What are the preventive techniques used in corrosion of metals?

Prevention of corrosion of metals :

  1. Covering the surface of metal with paint or by some chemicals like bisphenol which prevent the surface of metallic object to come in contact with atmosphere.
  2. Covering the surface of metal by other metals like tin or zinc that are inert or react themselves with atmosphere to save the metal.
  3. An electrochemical method in which a sacrificial electrode of another metal like magnesium and zinc etc., corrodes itself to save the metal.