This chapter provides a discussion of how informatics tools can address one of the fundamental historical developments in crystal chemistry, that of structure maps. Such maps serve as a means to explore how specific parameters associated with crystal and electronic structure can serve as a way to rationalize groupings, or classifications, relating structure and chemistry. Historically, structure maps have evolved through a variety of heuristic approaches that define a priori how parameters may be important, and then classifications are discovered as one populates these maps with data. The resulting clustering of data serves as a heuristic tool to rationalize new discoveries and new structure–bonding relationships.