This book brings together some of the growing number of research studies and inquiries into practice that have focused on the visual communication design aspects of diagrams used principally to inform the non-expert. This places it firmly in the domain of that viewer/user-centred field of endeavour called information design. Diagramming is a universal graphic 'language' used in almost all fields of human activity - thus there are many subject-specific 'dialects'. However a central thesis in this work is that there is a limited set of visual codes, which, through a virtually infinite range of potential combinations, provides a great variety of diagrammatic possibilities. However, in broad terms, most diagrams fall into a small group of generic types. Similar forms of the same type often go by different names - names sometimes derived from the field in which they are used. The cases presented in these chapters are necessarily from selected domains, but aspects of all the main generic types are dealt with to some degree. Thus the lessons learned can be transferred from the domain in which they are explored to other potential areas of application. The chapters are arranged into three sections. Section 1 mainly deals with theories on the morphological organization of diagrams and offers analyses of diagrammatic types. Section 2 Presents and describes some particular diagrammatic approaches. Section 3 is essentially about methods for designing diagrams. Understanding the organizational possibilities in diagrams can assist thinking about how to design new ones. Likewise methods for designing diagrams necessarily draw on theoretical underpinnings. So the difference in the nature of the content of these three sections may seem indistinct in some places. Nevertheless this general categorization indicates the broad intentions of the chapters they contain and therefore may be helpful to the reader. Whilst for the most part the authors are university-based design res