DFD

Motivation

A diagram that shows how data moves between processes, stores, external actors, and system boundaries.

Where it fits

This concept provides a shared vocabulary for designing, documenting, measuring, or operating software systems.

Mental model

Treat it as a structured tool: define the question being answered, use consistent terminology, and connect the result to decisions and follow-up work.

Practical use

DFDs help teams reason about trust boundaries, transformations, persistence, and integration without committing to code-level detail.

Common mistakes

• Using ambiguous definitions or units.
• Collecting or documenting information without connecting it to a decision.
• Failing to keep the artifact or measurement current as the system changes.

Related concepts

See the linked concepts in the knowledge graph for prerequisites and adjacent practices.