A Simple data flow diagram's purpose is to show the scope and boundaries of a system as a whole. It can be used as a tool for communication between a systems analyst and anyone involved in the system that serves as the starting point for redesigning a system. It is customarily started with a context diagram as level 0 of the Simple data flow diagram, a simplified representation of the entire system. After creating a DFD, you can add levels with additional information about a process. You can continue to add layers to the DFD, but you should keep them to a minimum.