<P> 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 . </P> <P> Some of the earliest evidence of salt processing dates to around 8,000 years ago, when people living in the area of present - day Romania boiled spring water to extract salts; a salt - works in China dates to approximately the same period . Salt was also prized by the ancient Hebrews, the Greeks, the Romans, the Byzantines, the Hittites, Egyptians, and the Indians . Salt became an important article of trade and was transported by boat across the Mediterranean Sea, along specially built salt roads, and across the Sahara on camel caravans . The scarcity and universal need for salt have led nations to go to war over it and use it to raise tax revenues . Salt is used in religious ceremonies and has other cultural significance . </P> <P> 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, only 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 . </P> <P> Sodium is an essential nutrient for human health via its role as an electrolyte and osmotic solute . Excessive salt consumption may increase the risk of cardiovascular diseases, such as hypertension, in children and adults . Such health effects of salt have long been studied . Accordingly, numerous world health associations and experts in developed countries recommend reducing consumption of popular salty foods . The World Health Organization recommends that adults should consume less than 2,000 mg of sodium, equivalent to 5 grams of salt per day . </P>

Where does salt come from in the world