Metamaterials: What Is Out There and What Is about to Come

A targeted discussion of the state of the art in the field of metamaterials' design, modeling and construction is presented. Only some of the most interesting aspects of the theoretical and experimental investigations available in the literature are described, by selecting the most innovative or methodologically interesting ones. After a preliminary analysis of these aspects, those which seem to be the most promising future research directions are sketched. The most important challenges in the field are delineated, in order to motivate the reader who wants to become acquainted with presented subject.