A salt is a compound formed when some or all the hydrogen ions in an acid are replaced by metal ions or ammonium ions. For example, zinc sulfate is the salt formed when zinc ions replace the hydrogen ions of sulfuric acid.
Most group 1 (I), group 2 (II), aluminium and zinc salts are white. They produce colourless solutions when dissolved in water. Transition metal salts generally produce coloured solutions when dissolved in water.