The drying of food is the world's oldest known preservation method, and dried fish can be kept for several years.
Stockfish is unsalted fish that is naturally dried by sun and wind out on the racks. It is mainly Cod that is used for drying, but also significant quantities of saithe, haddock and tusk are used.
Stock fish is Norway's longest sustained export commodity and has economically been the most profitable export item throughout the centuries. Ever since the Vikings, Norwegians have exported dried fish.
The fish is hung while there is still snow on the ground, mainly in March. This happens at the same time as the seasonal cod fishery takes place around the Lofoten Islands. The fish is on the racks for about 3 months. During drying, over 70% of the water evaporates, and the fish's nutritional content is significantly concentrated.