Common 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 is the main mineral constituent; the open ocean has about of solids per litre, a
salinity of 3.5%.
Salt is essential for animal life, and saltiness is one of the
basic human tastes. The tissues of animals contain larger quantities of salt than do plant tissues; therefore the typical diets of nomads who subsist on their flocks and herds require little or no added salt, whereas cereal-based diets require supplementation. Salt is one of the oldest and most ubiquitous of food seasonings, and
salting is an important method of
food preservation.