NaCl, or sodium chlorine (commonly known as salt), is an inorganic compound that is formed when sodium atoms and chlorine atoms interact with each other. Like most salts, NaCl forms with ionic bonding, which occurs when the valence electrons are transferred from one atom (which then becomes a positively charged ion) to another atom (which becomes a negatively charged ion).

In the example of NaCl, sodium (Na), in its outermost shell, has one electron, while chlorine (Cl) has seven. The sodium loses its one electron, which is then permanently transferred to the chlorine—the sodium becomes a positively charged ion, while the chlorine becomes a negatively charged ion (chloride). The sodium and the chlorine ions then exhibit an ionic bond, which results with the formation of the molecule known as NaCl.

NaCl is an odorless, white, soluble crystalline solid that has many commercial and industrial uses. It is most commonly used to add flavor to food, as well as to preserve it.