One of the graphical representations used to show the flow of data from source to destination is Data flow diagrams (DFD). DFDs are widely used for visual representation. When it comes to analyzing the process of data handling, DFDs are used to understand the entire structure of the data flow.

Let us understand the importance of DFDs using a simple example. Consider a case when someone decides to build a building. The very first thing he will do is hire an architect, who will analyze the building area and build the blueprint of the building structure. This blue print will be considered the base architecture of the building and the building will be built as per the blue print created by the architect.  The importance of making the blue print before starting the actual building is to understand the various aspects of the building, to understand the risk involved in the construction, and to decide how will it look like. Doing this helps to understand everything on paper first, and if any changes are required, they can be done easily on paper rather than during construction.

A similar concept applies to data architecture. It is always better to build the architectural blue print of the data before starting data architecture. To do this, a data flow diagram is used.

A data flow diagram uses its own collection of symbols to show the flow of data. See the following diagram for the various symbols used in data flow diagrams::

	External entity
	Process
	Data store
	Data flow