Salt

A salt in chemistry is a solid at room temperature, made of metal-ions and non-metal-ions¹. It can only dissolve in polar solvents like water. Some salts are pH neutral (eg. NaCl = rock salt used for cooking), some are basic (eg. NaOH) and some are acidic (eg. NaH₂PO₄). Some salts are very solvable, some are almost insolvable. The higher the temperature of the solvent, the more of a salt can dissolve.

Not everything that is ionized in water is a salt. HCl (a strong acid), and vinegar/acetic acid CH₃COOH (a weak acid), form ions as well, but are molecular substances.

¹ There are a few exeptions to this rule. NH₄⁺, the ammonium-ion forms salts without a metal-ion (eg. NH₄Cl, salmiac salt).