The author explains the electrochemical process that leads to corrosion of metal objects (iron and other metals) from the action of water, oxygen, and salts. He refers to his own experience in the Norvegian Technological Museum in Oslo and deals with various kinds of protection against corrosion; it is very important to maintain a low relative humidity in the storage rooms. Coating agents can be used for surface protection, e.g., color coating or the so-called temporary protective aids based on oil, wax, or fat. -- AATA