Salt is essential for life in general, and saltiness is one of the basic human tastes. Salt is one of the oldest and most ubiquitous food seasonings, and salting is an important method of food preservation.
Salt is processed from salt mines, and by the evaporation of seawater (sea salt) and mineral-rich spring water in shallow pools. Its major industrial products are caustic soda and chlorine; salt is used in many industrial processes including the manufacture of polyvinyl chloride, plastics, paper pulp and many other products. Of the annual global production of around two hundred million tonnes of salt, about 6% is used for human consumption. Other uses include water conditioning processes, de-icing highways, and agricultural use. Edible salt is sold in forms such as sea salt and table salt which usually contains an anti-caking agent and may be iodised to prevent iodine deficiency. As well as its use in cooking and at the table, salt is present in many processed foods.