Cations are ions that carry positive changes while anions are negatively charged ions. Ions can also be categorized as monatomic or polyatomic.
Monoatomic ions are ions whose atoms are derived from a single element. Polyatomic ions are ions whose atoms are derived from more than one chemical element.
For example, Sodium ion (Na+) is a monatomic cation while Phosphate ion or Orthophosphate (PO4³-), is a polyatomic anion.