Data Flow Diagram - DFD Levels, Symbols, Case Study, Tutorial, Example,

The purpose of Data Flow Diagrams is to show the “flow” and transformation of data through the system.  These diagrams are used as a visualization tool to help the audience get a better idea of what exactly is going on in the system.     A Context Diagram is shown next, which is the general overview of each of the different agents interacting with the system.    The Level 0 Diagram shows some more details about which processes each of the agents will be interacting with.  Arrows are drawn to show the flow of data between the agents and processes.    Following the Level 0 Diagram are Level 1, Level 2, Level 3 and Level 4 Diagrams.  These Diagrams further break down each of the processes that are involved with the system, each showing more detail the further down the level is.

A Data Flow Diagram (DFD) is a diagrammatic representation of the information flows within a system showing How information enters and leaves the system  What changes the information  Where information is stored The purpose of a DFD is To show the scope and boundaries of a system  To show that the whole system has been considered May be used as a communications tool between a systems analyst and any person who plays a part in the system To act as the starting point for redesigning a system