Acid salt: The cation produced by ionization contains hydrogen ions (with the nature of metal ions) in addition to metal ions or NH4+, and the anion is a salt of acid ions.

Basic salt: A basic salt refers to a salt in which anions generated during ionization include hydroxide ions in addition to acid ions, and cations are metal ions (or NH4+).

Ordinary salt: salt containing neither ionizable hydrogen ions nor hydroxyl ions.

Double salt: a salt consisting of two metal ions (or ammonium ions) and one acid ion.