Data flow diagram
A Data Flow Diagram (DFD) is a graphical representation of the flow of data through an information system (ie: shows business processes and the data that flows between them). It illustrates what kinds of data will be input and output from the system, where the data will come from and go to, and where the data will be stored. A DFD is often an elaboration of a context diagram to show some of the detail of the system that was first illustrated through the context diagram.
Notation:
- A function or process is a circle
- External entities are shown as squares
- Inputs/outputs are a rectangle
- data flows are shown as arrows
- data store/files/databases are double lines
Example data flow diagram (PDF)
