Table salt is a mineral composed mainly of sodium chloride (NaCl). This is a chemical compound, one of a large number of salts. Salt in its natural form as a crystalline mineral is known as rock salt or halite.
When salt (sodium chloride) is mixed with water, the salt dissolves into the water, creating a saline solution. Salt is present in vast quantities in seawater, where it is the main mineral constituent. The open ocean has about 35 grams (1.2 oz) of solids per litre, a salinity of 3.5%.