Business Analyst: What is data flow diagram (DFD)?

DFD — shows how data moves through a system.

Levels:

• Level 0 — context diagram (high-level).
• Level 1 — major processes.
• Level 2 — detailed processes.

Symbols:

• Circle — process.
• Rectangle — external entity.
• Open-ended rectangle — data store.
• Arrow — data flow.

Level 0 Example:

Benefits:

• Visualizes data movement.
• Identifies data stores.
• Shows data transformations.
• Supports system design.