DFD explanation

DFD (Data Flow Diagram):

DFD is a designing concept used to transform a textual problem into pictorial or graphical form in a hierarchical order.

It describes how   data and information are transformed in a system in a pictorial manner.

DFD provides a complete description of:-

      (a) What data are processed?

       (b)  How processing is done?

(c)  What data are stored?

(d) Which stored data are used and

 (e)  Where the result flows?

DFD is top-down designing approach in which

(a)A high-level function is decomposed into a set of easy understandable function.

(b)Each function performed by system is analyzed and decomposed into more detailed description.

• A  DFD models a system by using external entities from which data flows to a process which transform the data  and creates output data flow which go to other processes or external entities or data stores .  From data stores, stored data may also flow to process as inputs.