This article provides an overview of and general introduction to the present understanding of the electronic structure of
liquids. Special emphasis is laid on the role played in recent years by ab-initio simulation methods to get insight into the
strong interplay between electronic and structural properties typical of the liquid state. Discussion of physical systems is organized around the illustration of few selected results for prototype classes of liquid systems corresponding to the five types of electronic bonds: metallic, covalent, ionic, hydrogen, and van der Waals.
