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A Beginner’s Guide to Data Flow Diagrams

Find any professional sportsperson or professional what they did to become successful and they’ll tell you they were able to master a technique. Through determining the habits that led to success and which did not and enhancing their effectiveness, efficiency and productivity at work.

Implementing a process in departments, businesses or even a group is different as enhancing your personal procedure. With all the moving parts, how can you monitor each part of your company’s process and what can you do to improve it?

Data flow diagrams offer an easy, effective method for companies to comprehend how to improve, implement, and perfect new systems or processes. These are visual depictions of the procedure or system, and therefore aid in understanding and modify.

Before we look into how flow diagrams of data can aid in the improvement of any of your company’s processes or systems Let’s look at what exactly it is.

What exactly is a Data flow Diagram (DFD)?

The data flow diagram (DFD) is visual representation of information flow that flows through an entire system or process. DFDs aid in understanding the operation of a system or process to uncover potential problems increase efficiency and improve processes. They can range from basic overviews to more complex, detailed visualizations of a process system.

DFDs were popular in the 1970s, and remain popular because they are easy to comprehend. Visualizing the way in which a system or process operates can draw attention and communicate complex concepts more effectively than blocks of text. As such, DFDs are able to assist any person understand the process’s operations and logic.

There are two kinds of DFDs that are physical and logical. Logical diagrams show the flow of information through a system, such as the source of data and where it is taken and how it is changed and how it finishes at.

Physical diagrams illustrate the process of moving information throughout a system, such as how the system’s hardware, software employees, files, and customers influence the circulation of data.

There are physical or logical diagrams to represent the same information flow or combine them to comprehend an entire system or process at an even more detailed scale. However, before you utilize a DFD to analyze your process or system’s flow of data, you must to understand the most common symbols or notations used to explain the flow of information.

Data Flow Diagrams Symbols

Data Flow Diagram symbols are notations that are standard such as rectangles, circles or arrows as well as short-text labels that define the process or system’s direction of data flow and data inputs, as well as data outputs, storage points, as well as its diverse sub-processes.

There are four main methods of notation that are used for DFDs: Yourdon & De Marco, Gene & Sarson, SSADM and Unified. They all use the identical labels and similar forms to depict the four major components of the DFD — an external entity processing data store, external entity, and data flow.

External Entity

External entities, also known as are also referred to as sources, terminators, actors, or sinks are a system or process that transmits or receives information to as well as from the system in which it is diagrammed. They are either sources or destinations of information which is why they’re often placed on one of the edges. Entity symbols that are external are the same across different models, with the exception of Unified which employs an illustration of a stick figure instead of a circle, rectangle or square.


Process is a process which manipulates process of data as well as its flows through taking inbound data, altering it, and then producing output using it. The process may accomplish this by making calculations and employing logic to sort the data or alter its direction of flow. Processes typically begin at the upper left corner in the DFD and end on the bottom left on the graph.

Data Store

The data stores store data for future use like a collection of documents ready to process. Data inputs are processed through a process , and finally through a data store , while data outputs flow through the data store through an process.

Data Flow

The data flow describes the route the information of the system travels from external sources through processes and storage of data. With the help of arrows and concise labels the DFD can help you understand the direction of data flow.

Before you begin constructing diagrams of data flow, you must to follow these four guidelines to make a reliable DFD.

1. Every process should include at least one input and an output.

2. Every data store should include at minimum one flow of data in and one flow out.

3. The data stored by a system has to go through a procedure.

4. Every process within a DFD must be linked to another data store or process.

The levels of data flow diagrams

DFDs vary from basic overviews, to elaborate and granular representations of a process or system that have multiple levels. They begin at the level 0. The most popular and easy to understand DFDs are the level zero DFDs or context diagrams. They’re digestible, high-level representations that show the way information flows throughout an entire system or process meaning that anyone can comprehend the concept.

Level 1 Context Diagram

This DFD level focuses on the top-level operations or processes within the system and the sources of data that are flowing to or from them. The Level-0 charts are intended to be easy, clear diagrams of a procedure or system.

First Level: Decomposition of Process

While the level 1 DFDs aren’t necessarily broad overviews of a process or system They’re also more specific – they breakdown the single processes into smaller subprocesses.

Level 2: Deeper Dives

The next stage of DFDs go deeper into detail , breaking each level 1 process down into subprocesses that are granular.

Level3: Complexity Increasing

The higher numbers of Level 3 DFDs are not common. This is due in large part to the level of detail required, which defeats the primary goal of being easy to comprehend.

How to create an a Data Flow Diagram

Choose a method or system.
Sort related business activities into categories.
Create a context DFD.
Check your work.
Create diagrams for children.
Develop processes to the Level 1. DFDs.
Repeat as often as you need to.

1. Choose a process or system.

Start by choosing a particular process or system you’d like to examine. Although any process or system could be converted into an DFD however, the more complex the process, the more complex the diagram will become and the more difficult to understand. When you can, begin by defining a single operation or process that you’re hoping to enhance.

2. Classify related business activities.

Then, you can categorize the processes that are related to the process as external, such as data flow processes and data storage.

Think about a restaurant’s ordering system. Customers are outside entities, the ordering system for food is a procedure and the interaction between people and systems (which can be both directions) can be described as the flow.

Another thing to note? The ordering system is also an data store, and to create the SSADA model, it’s drawing it in an elongated rectangle and two lines running horizontally within to indicate its dual purpose.

3. Draw Context DFD.

The time has come to start sketching. DFDs can be made manually, using online templates for free or by using browser extensions.

Begin with a simple DFD of Level 0: Begin with your system or process first, and then map the most essential flow and connections.

4. Check your work.

Before you dive into more complicated DFDs be sure to review the work you’ve completed to ensure that it’s accurate and complete. If you’ve not included (or added) an entity, process or flow the next level of DFDs might not be logical and you might be required to begin again.

5. Make child-friendly diagrams.

For each system or process that you have described by Your Level 0 DFD Create an entirely new diagram that has its own flow and entities. In the end, you can use these diagrams to link processes.

6. Develop processes to level 1 DFDs.

Utilizing your child diagrams, you must map out more specific connections between each of the processes. In the restaurant we’ve discussed it could be a matter of digging deeper into the ordering system as well as its relationship to managers, suppliers customers, as well as the kitchen staff.

7. Repeat as often as you need to.

Each step — regardless of how big or small , can be transformed into an level 0 context diagram, and the cycle can start with a new perspective. Repeat the steps as necessary to produce the number of DFDs as needed or break the process down further to produce the Level 2, 3, etc. DFDs.

Enhancing Your Process

Although there’s no such thing as an “perfect” information flow chart, regular practice can streamline the process and provide crucial insights into what’s working, which isn’t, and where your company could implement improvements that will have the greatest impact.

Your best bet? Make sure you keep simple. Begin with context, then build the processes that are connected and then repeat as needed to define important connections, flows, and the various entities within your company.