Imagine food without salt! You would not even think of eating it. Salt is a necessary ingredient in every recipe. Common salt, in fact, is a compound of sodium and chlorine. It also contains several minerals such as iodine. One atom of sodium combines with one atom of chlorine and forms one molecule of sodium, chloride. To obtain salt, salt water from sea is led into wide, shallow basins. After certain treatments the water is allowed to flow into a succession of basins. The deposits of sodium chloride is then processed and purified to make salt. How do we get common salt? It has been estimated through scientific analysis that the water of the seas contains about four and a half million solid cubic miles of salt. All these salts have reached into the seas from the Earth. The rainwater and molten snow water dissolve minerals from rocks and flow down through the rivers into the oceans and seas. These are main sources of salt deposits in ocean and seawater. It has been found that on the whole seawater contains about 3%-3.5% of common salt. But millions of years ago, evaporation took place from the water of bays, which were cut off from the sea and became salt lakes. Since sea has an abundant quantity of salt, it remains the main source of salt-supply. To obtain it through artificial means, water is led into wide, shallow basins about 3 feet deep. In the first one the solid impurities like sand, mud and tiny living creatures get settled. Calcium sulphate is also separated from the water in this basin. The water then flows into a succession of basins and evaporates there. In the process, sodium chloride is deposited in the basin, which is then collected, dried, refined and purified. In cold countries, a different method is used for the extraction of salt. The seawater is allowed to freeze, since the ice from frozen seawater does not incorporate the molecules of salt. These accumulate in the unfrozen water under the ice and make it saltier. The floating ice is gradually removed and further frozen until only a small quantity of highly saline water remains. This is collected and evaporated by means of artificial heat and salt is collected. There are many salt deposits in the world. The salt formations of Kansas, Oklahoma, Texas and New Mexico in the U.S.A. cover an area of about 100,000 square miles and are the largest in the world. Common salt is basically used for flavouring and preserving food.