A Data Flow Diagram (DFD) is a graphical tool that illustrates the flow of data between processes in a business, clarifying system requirements and identifying major transformations. It employs various symbols to represent sources, processes, data flow, and databases, and is categorized into levels from context to more specific representations. DFDs facilitate understanding of system boundaries, data movement, and interprocess relationships, following conventions for clarity.

1. SSAD
DATA FLOW DIAGRAM
Prepared By:
MUKESH MAHTO
MBA-IT

2. DATA FLOW DIAGRAM
• A “Data Flow Diagram” is a graphical representation that
depicts information flow, i.e. it represents the flow of data
between different processes in a business.
• The main purpose of DFD is to clarify system requirements and
identify major transformations that will be carried out in a
system.
• DFDs are used not only in Structured Systems Analysis and
Design but also as a general process modeling tool.
• It is also known as “Bubble Chart”.

3. DFD– Why?
• It gives the summary of the entire system.
• Easy to understand.
• It supports the logic behind the data flow within the system.
• It can also provide a detailed description of the system
components.
• It represents an information system from the viewpoint of data
movements – inputs & outputs.
• It defines the boundaries of the entire system.
• Also, the ability to represent the system at different levels is an
added advantage.
• It parallely shows the relation between a particular process
and its database.

4. Components of DFD
• Various symbols are used in a Data Flow Diagram –
1. - It represents “source” or “destination” of data.
2. - It represents the process that transforms the data
flow.
3. - “Arrow” represents data in motion.
4. - It represents data at rest or database.

5. Levels of DFD
• Level Zero or Context Level DFD – It represents the complete
system with all modules. It is the highest abstraction level DFD.
• Level 1 DFD – The Level 0 DFD is broken down into more
specific i.e. Level 1 DFD. It depicts basic modules in the system
and the flow of data among various modules.
• Level 2 DFD – At this level, DFD shows how data flows inside
the modules mentioned in Level 1.
• Thus, higher level DFDs can be transformed into more specific
lower level DFDs with deeper level of understanding unless the
desired level of specification is achieved.

6. Rules / Good Conventions
• Arrows should have direction as to know where the data
flows.
• Arrows should be labeled as to know what kind of data is
flowing.
• Less number of processes.
• Number the processes.

7. EXAMPLE – Context Level DFD

8. EXAMPLE – Level 1 DFD

9. EXAMPLE – Level 2 DFD

10. THANK YOU