From ancient times, humans have used diagrams to represent and communicate, whether through cave drawings, sketches or schematics. In this age where remote international knowledge-working is more commonplace, developing our skills for effectively and meaningfully communicating ideas is perhaps more important than ever. Diagrams are a critical part of this, often being used to describe organisations, software and projects. This makes scientific sense as they can be useful aids for describing, interpreting and reasoning about many kinds of systems. In software development, practitioners make use of system architecture diagrams, mind maps, and even clustered-sticky-notes-in-a-retrospective, to signify relationships between important items, topics or events. Diagrams are particularly good for describing complexity because they: - Are external representational support to cognitive processes. - Make topics simpler, leading to reduced search space and fewer cases to be computed over, by including minimal salient information. - Are manipulated in order to profile known information in an optimal fashion. - Make abstract properties and relations cognitively accessible. - Can be in a public space, enabling collective and temporally distributed forms of thinking. - Facilitate perceptual "free rides" in inference, making relations evident that might not be obvious in a different representation such as text. In this workshop, Guy will interactively share his research findings about diagrams, going from the philosophy of diagrams to potential future developments for diagramming. This journey will focus on the historical development of technical diagrams, discuss present-day diagramming practices, and provide advice for creating improved diagrams based on graphical grammars. Types of diagrams explored will include examples from concept mapping, organisational charts, value stream maps, the Cynefin framework, and security and software architecture diagrams. On the way, we will explore the theory with practical activities, creating new and improved diagrams. Better diagrams can support better communication, especially relating to complex systems, so this workshop is well worth attending!