- Diagrams are useful tools for communication that can help convey complex ideas more effectively than words alone. Diagrams used as code, where diagrams are treated as an integral part of documentation alongside code, provide several benefits including simplifying communication, onboarding others efficiently, and helping to structure information. The author recommends starting to include diagrams in documentation by exploring parts of a system with many terms and concepts, and treating diagrams like reusable code by embedding them and version controlling them. This helps share knowledge and avoids duplicating effort.