Data Flow Diagrams

A data flow diagram (DFD) is a graphical representation of the "flow" of data through an information system, modelling its process aspects. Often they are a preliminary step used to create an overview of the system which can later be elaborated.DFDs can also be used for the visualization of data processing (structured design).

A DFD shows what kinds of data will be input to and output from the system, where the data will come from and go to, and where the data will be stored. It does not show information about the timing of processes, or information about whether processes will operate in sequence or in parallel (which is shown on a flowchart).

System Flowchart

What is a System Fowchart?
System flowcharts are a way of displaying how data flows in a system and how decisions are made to control events.
To illustrate this, symbols are used. They are connected together to show what happens to data and where it goes. The basic ones include:

Symbols used in flow charts
Note that system flow charts are very similar to data flow charts. Data flow charts do not include decisions, they just show the path that data takes, where it is held, processed, and then output.

Flowchart

What is a Flowchart?

A flowchart is simply a diagram which shows the breakdown of a task or system into all of the necessary steps.

Each step is represented by a symbol and connecting lines show the step-by-step progression through the task.

Have a look at the diagram below. It shows the process of ordering a burger.

There is a clear start, a series of steps, a clear direction of flow and a clear end or finish point.

This is a very simple flowchart. For some tasks or systems, the flowchart can be very complex and detailed.