Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in its natural form as a crystalline mineral is known as rock salt or halite. Salt is present in vast quantities in seawater, where it serves as a major source of sodium and chloride ions for marine life and as a desalinating agent for producing fresh water from seawater.
Most ingested salt is in the form of sodium chloride, but other compounds such as magnesium sulfate and potassium iodide are sometimes added to table salt. The iodine added to salt has been shown to improve human health in areas where there is little iodine in the diet. Some jurisdictions require that certain proportions of these other salts be included in packaged table salt sold within their borders.
The major use of salt is in the production of chlorine and caustic soda (sodium hydroxide) which are used in many industrial processes, including the manufacture of paper, textile, detergents, plastics and construction materials like cement. Sodium chloride is also used to de-ice roads and sidewalks during winter weather conditions. Rock salt may also be ground into an edible powder known as “seasoned” or “kosher” salt which is used to add flavor to food.
Salt has been used since antiquity both for culinary purposes and as a preservative. It was once believed that Salt had curative powers and was used extensively in ancient times for medicinal purposes, although modern science has found no evidence supporting these claims. Today, Salt continues to be an important commodity with many uses beyond its original purpose as a flavoring agent or preservative.