: Cations:  metals  :  alkali metal ,  alkaline earth metal ,  transition metal ; Anions:  halides :  chloride  (Cl − ),  bromide  (Br − ),  iodide  (I − ); Polyatomic  /  Organic : Cations: ammonium,  pyridinium ; Anions:  tosyls ,  trifluoromethanesulfonates ,  methylsulfate ...     Current market   The annual