Data Flow Diagrams Basic Symbols

Flowcharting is a tool used for analyzing a process that helps you present the process in terms of individual events and activities using symbols to display the logical relationship between the processes to help in easier and better understanding of the processes.

DFD’s are used to show the flow of data in an organization from the internal source through the processes required until the data goes to the storage. While flowcharts show a clear and concise presentation of a system by breaking it into all stages, DFD’s give the overall picture of the organization or process. Data Flow Diagrams are used for documenting existing systems and designing new ones.

Data flow diagrams (DFD)

A DFD will use for symbols to show the flow of data:


This element of a data flow diagram uses a Rectangle symbol to denote the source or destination of data. When an entity provides data into a system it is called the source but when it denotes the destination it is called the sink. Entities are considered external forces in an organization.In some cases they are called terminators. Their use in a Data Flow Diagram is to show where a process begins or where it ends.

Data flows.

Are symbols in a DFD that show flow of data from one point to another i.e. from the entity to the process etc. They indicate where data moves or the direction for a process from one event to another. It portrays the interface between one component to another. The symbol used  to show data flow is an arrow.


This is the manipulation or transformation work whereby computations, transformations, decisions and directions are made. Here, the symbol will show where data conversion takes place so that input can be changed into output.The symbol used to show process is a square with rounded corners or (sometimes a complete circle).

Data store.

This is where data is stored between or after processes for later retrieval for another process or to another one. These data stores will use a symbol drawn like a rectangle that has the right hand side missing (Open on the right).

The importance of the Data flow symbols is that they help identify and determine the external sources in an organization. They help know who brings in the data, where it comes in and the type of data that a process deals with. Further than that it will indicate who the recipients are and what type of data they receive. The type of processing that happens is also indicated therefore it easily describes what a department does and how it does it processes the data.


Basically, the importance of the symbols is to indicate what happens where. Which means that by just a look at a DFD a person will be able to tell what goes on in an organization.

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