Salt that is meant for human consumption refers to sodium chloride. Both table salt and salt tablets contain sodium chloride and not just sodium. They can both contain other naturally present or added minerals.
Table salt usually refers to rock salt, which is obtained from underground mines. It should contain at least 97% of sodium chloride and can also contain other natural or added substances.
Sea salt is obtained from the sea. The main ingredient is sodium chloride and it can naturally contain 0.2 to 10% of other salts, such as calcium, potassium, and magnesium salts of chloride and sulfate.
In some countries, iodine is added to rock or sea salt (iodized salt) to prevent iodine deficiency.
Salt tablets are available as:
- commercial products, which contain sodium chloride, and may or may not contain other minerals, such as potassium and magnesium, in various amounts (depending on the brand); they are popular among long-distance runners
- prescribed supplements, usually named "sodium chloride tablets," in which the only active ingredient is sodium chloride and which are intended for various health conditions.
Salt substitutes, which mainly contain potassium chloride, are commercially available or prescribed and are intended to use instead of rock or sea salt to prevent excessive sodium intake.