What is a Data Flow Diagram?
Data Flow Diagram: A data flow diagram is the graph that shows flow of data values from their sources in objects in the course of processes which transform them to their destinations in other objects.
It does not show how values are controlled while computation. The Data Flow Diagram shows functional relationship of values computed by a system. DFD contains processes which transform data, data flows which move data, actor objects which produce and consume data and data store objects which store data passively.