What it is
A Diagram is a visual representation used to explain structure, relationships, scope, or flow between systems, processes, or components.
Diagrams do not define rules, instructions, or proof. They exist to help people understand how things fit together, especially when text alone is insufficient.
A diagram is a visualization, not a photograph. It represents concepts and relationships rather than physical reality.
Why it exists
Some information is easier to understand visually than in writing. Diagrams help people quickly grasp how systems interact, where boundaries exist, how data moves, or how work flows at a high level.
In compliance, security, and operational contexts, diagrams support understanding during planning, audits, reviews, onboarding, and communication with stakeholders.
Diagram types by purpose
Different diagrams answer different questions. Common types include:
- Architecture Diagrams
Show system structure and major components. - Data Flow Diagrams (DFDs)
Show how data moves between systems, services, or boundaries. - Boundary / Scope Diagrams
Show what is in scope, out of scope, or within a defined boundary. - Process Diagrams
Show stages or steps in a workflow at a high level. - Relationship Diagrams
Show access, trust, or dependency relationships between entities.
What diagrams are used for
Diagrams are used to explain and communicate design, intent, and structure.
They are often referenced by policies, plans, processes, or procedures.
Diagrams may support audits or reviews but are not proof by themselves unless paired with artifacts.
Common confusion
Diagram vs Policy
A policy defines rules or required outcomes.
A diagram explains structure or relationships.
Diagram vs Procedure
A procedure provides step-by-step instructions.
A diagram shows flow or structure, not detailed execution steps.
Diagram vs Process
A process defines how work is performed.
A process diagram visualizes stages or sequence without replacing procedures.
Diagram vs Artifact
An artifact proves something happened or exists.
A diagram explains how something is designed or related.