The building of ionic complexes by consecutive reactions of ligand coordination to the charged ion offers an attractive way to study complex systems. Modem experimental techniques allow the properties of complexes to be measured, successively from the bare ion to the condensed phase, or to restrain large molecular aggregates. Experiments provide direct or indirect information on structure, thermodynamics, reactivity, electron detachment properties, and molecular vibrations. The complementary, high-level ab initio studies supplement experimental findings, enhancing the interpretation and helping to remove the often-present ambiguities. The most distinguishing property of charged complexes is the formation of ligand shells around the ion. Such an organization determines properties of both the core ion and its ligand environment. Theoretical studies of nature of interactions lead to a simplified description of bonding and provides the base for developing the chemical intuition.