Data Flow Diagrams (DFD) Skill

Purpose

Visualize how data moves through a system. DFDs show what the system does with data, unlike Flowcharts which show control flow (sequence).

When to Use

• Understanding legacy systems.
• Analyzing data privacy (where does PII go?).
• Designing integrations.
• Security auditing (identifying trust boundaries).

DFD Notation (Gane & Sarson or Yourdon)