A Data Flow Diagram (DFD) is a graphical representation used to illustrate the flow of data within a system. It is a tool employed in systems analysis and design for describing business processes within an information system. A DFD visually represents the data movement across different entities in a system, and it highlights the sources and destinations of data flows, processing points, and data storage locations.
DFDs are structured into different levels of detail to provide insights into various system processes. The initial and broad overview is the Level 0 DFD, often referred to as a Context Diagram, which shows the system as a single process with external entities interacting with it. These can then be broken down into more detailed diagrams (Level 1, Level 2, and so on) that illustrate the sub-processes and finer details of each part of the system.
The primary notations used in a DFD include:
Processes: Illustrated as circles or rounded rectangles, indicating where data transformation occurs.
Data Flows: Depicted by arrows, showing the direction of data movement.
Data Stores: Represented as open-ended rectangles, suggesting where the data resides.
External Entities: Shown as squares or rectangles, representing external sources or destinations of data.
DFDs are a fundamental part of structured methods of system analysis, aiding in understanding and documenting data-driven processes to improve system functionality and efficiency.
