DATA FLOW DIAGRAM

1. By : Garishma Bhatia

2.  A data flow diagram also known as DFD.
 A DFD is a graphical representation of the
"flow" of data through an information
system.
 It uses defined symbols like rectangles, circles
and arrows, to show data inputs, outputs,
storage points and the routes between each
destination.

3.  A DFD shows what kind of information will be
input to and output from the system.
 where the data will be stored

4.  External entity: an outside system that sends or
receives data.
 Process: any process that changes the data.
 Data store: files that hold information for later
use.
 Data flow: the route that data takes between
the external entities.

6.  Each process should have at least one input
and an output.
 Each data store should have at least one data
flow in and one data flow out.
 Data stored in a system must go through a
process.
 All processes in a DFD go to another process
or a data store.

7.  There are mainly three types of data flow
diagram:
- level 0
- level 1
- level 2

8.  DFD Level 0 is also called a Context Diagram.
 It’s a basic overview of the whole system.

9.  DFD Level 1 provides a more detailed of the
Context Level Diagram.

10.  DFD Level 2 then goes one step deeper into
parts of Level 1.
 It may require more text to reach the
necessary level of detail about the system’s
functioning.

12.  Progression to Levels 3, 4 and beyond is
possible, but going beyond Level 3 is
uncommon

13.  A DFD is often used to create an overview of
the system without going into detail, which
can later be elaborated
 DFDs can also be used for the visualization of
data processing.

14. THANK YOU