A flowchart is very simply a diagrammatic representation of the flow of information. Now this flow of information could be in a Information Processing System or just an explanation of how an algorithm works. A flowchart typically shows the flow of data in a system, detailing the operations in a pictorial format which is easier to understand than reading it in a textual format. Besides, a flowchart quite simplistically shows the sequence of the operations taking place in the system too.
Hence a flowchart helps in solving a problem by offering an easy to understand graphical solution that shows the different operations which are the steps of the solution and the sequence of those operations. Hence a flowchart is used extensively in IT and ITES companies. A flowchart can be compared to the blueprint of a building. It shows what the structure of the building is (or algorithm or problem or the information processing system) and shows the building blocks of the structure which comprise the information needed to arrive at the solution through sequential blocks of data. It wouldn’t be wrong to say a flowchart is a sort of a ‘must’ to document and explain complex and lengthy programs.
A flowchart has certain rules that need to be followed while drawing it. These rules are given by a governing body known as the ANSI (American National Standard Institute). There are certain standard ways of drawing a flowchart with the symbols prescribed by ANSI. Knowledge of these symbols is necessary if u want to draw a flowchart. These flowchart symbols are given below:
The rectangle in a flowchart denotes processing function or a just a computational step while processing.
- The oval is used to denote start or end of a program.
- The parallelogram is used to denote the input or output steps of a program.
- 
Connector
in a flowchart.
- This is used to denote a magnetic tape.
- This is used to denote a magnetic disk.
- This is used to denote an off-page connector.
- This is used to denote “ Display “
- 
These
arrow lines are called flow lines.
These are the basic symbols used generally. Now, the basic rules for drawing a flowchart with the above symbols are that:
Ø The flowchart is to be read left to right or top to bottom.
Ø A process symbol can have only one flow line coming out of it.
Ø For a decision symbol, only one flow line can enter it, but multiple lines can leave it to denote possible answers.
Ø The terminal symbols can only have one flow line in conjunction with them.
A simple example of a flowchart of a purchase and quality inspection routine is below:
photo