Sea salt, salt obtained by the evaporation of seawater, is used in cooking and cosmetics. It is historically called bay salt or solar salt. Generally more expensive than table salt, it is commonly used in gourmet cooking and specialty potato chips, particularly the kettle cooked variety (known as hand-cooked in the UK/Europe).

Mineral salt has long been mined wherever it was available; the salt mines of Hallstatt go back at least to the Iron Age. However, there are many places where mineral salt is not present, and the alternative coastal source has also been exploited for thousands of years. The principle of production is evaporation of the water from the sea brine. In warm and dry climates this may be accomplished entirely by using solar energy, but in other climates alternative and often expensive fuel sources must be used. For this reason, modern sea salt production is almost entirely found in Mediterranean and other warm, dry climates.

Such places are today called salt works, instead of the older English word saltern. An ancient or medieval saltern could be established where there was:

A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, it means a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean. It is also used sometimes to describe a large saline lake that lacks a natural outlet, such as the Caspian Sea.

Arctic (belonging to the Arctic Ocean) and Antarctic (Southern Ocean) seas, as well as some other seas freeze in winter. This occurs below the freezing point of pure water, at about -1.8 °C (28.8 °F). Frozen salt water becomes sea ice.

Humans navigated seas from antiquity. Ancient Egyptians and Phoenicians navigated the Mediterranean Sea and the Red Sea. Hannu was the first see explorer of whom there is any information. He sailed along the Red Sea and further to the Arabian Peninsula and the African Coast around 2750 BC. In the 1st millennium BC, Phoenicians and Greeks established colonies all over the Mediterranean, including its outlets like the Black Sea. The seas along the eastern and the southern Asian coast were used by Arabs and Chinese for navigation, and the North Sea and the Baltic Sea were known to Europeans in Roman times. Other seas were not used for navigation in the antiquity and were actually discovered.

Salt, also known as table salt, or rock salt, is a crystalline mineral that is composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of ionic salts. It is essential for animal life in small quantities, but is harmful to animals and plants in excess. Salt is one of the oldest, most ubiquitous food seasonings and salting is an important method of food preservation. The taste of salt (saltiness) is one of the basic human tastes.

Salt for human consumption is produced in different forms: unrefined salt (such as sea salt), refined salt (table salt), and iodized salt. It is a crystalline solid, white, pale pink or light gray in color, normally obtained from sea water or rock deposits. Edible rock salts may be slightly grayish in color because of mineral content.

Chloride and sodium ions, the two major components of salt, are needed by all known living creatures in small quantities. Salt is involved in regulating the water content (fluid balance) of the body. The sodium ion itself is used for electrical signaling in the nervous system. Because of its importance to survival, salt has often been considered a valuable commodity during human history. However, as salt consumption has increased during modern times, scientists have become aware of the health risks associated with too much salt intake, including high blood pressure. Therefore health authorities have recommended limitations of dietary sodium. The United States Department of Health and Human Services recommends that individuals consume no more than 1500–2300 mg of sodium (3750–5750 mg of salt) per day depending on age.