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A flowchart diagram or just flowchart is a term generically used to refer to a diagram which shows the flow of a process (step by step).  More specifically a flowchart refers to a very specific type of structured workflow diagram which has been adopted by the International Organization of Standardization (ISO) and updated in 1985 with ISO 5807.

The flowchart is very similar in uses and functions as the UML activity diagram and the BPMN process diagram.

The flowchart diagram is drawn using a set of standard flowchart symbols including:

Symbol Name	Visual Depiction	Description
Flow line		The flowline represents the standard connector of the rest of the symbols in a flowchart.  It is terminated with an arrow to show the direction of the flow/process (generally top to bottom or left to right).
Terminal		This flowchart symbol represents either the beginning of the flow or the end of the flow.  A flowchart should have only one beginning symbol.
Process		The process flowchart symbol represents an action or activity which takes place at the given step in the process. Generally used to depic an action which takes place in the system or which uses the system.
Predefined Process		The flowchart pre-defined process symbol depicts the fact that this step is decomposed in detail in a different diagram or page. If a given sub-process or segment of a process is reused, it can be defined once and then specified again using the pre-defined process symbol.
Decision		The flowchart decision symbol is very similar to the decision symbol of other diagraming techniques and issued to show where a given process or flow can split  into two or more branches based on a decision condition.
Input or Output		This flowchart symbol depicts that at this point in the flow data is either entred into the process/system or data is being output from the process/system.
Manual Input		The manual input flowchart symbol is used to show that a human is performing data entry or providing information to the system.
Data file or Database		The database flowchart symbol is used to depict storage of data (it could be a database, a file, etc.) and it could be used either to read data from or write data to.
Document		The document flowchart symbol represents a single document (ex: PDF, Word, etc.) used within the flow being documented.  If multiple documents are used, multiple document symbols can be overimposed and slightly offset.
Manual Operation		The manual operation flowchart symbol is used to show that a user performs a manual operation within the flow which is other than simply data input.
On-page Connector		When a flowchart becomes too complicated and flowlines cross each other, an on-page connector can be used to show where to connect next without crossing lines.
Off-page Connector		When a flowchart becomes too large to fit on one page, the off-page connector symbol can be used to show where the flow leaves off on one page and then where it picks-up on a different page.
Initialization		The initialization symbol represents a step in the process (generally at the beginning) where a certain system routing or processed needs perform preparation/initialization activities.

When to use a Flowchart

Flowcharts are helpful whenever the problem domain you are tackling involves process or workflow or whenever you are trying to depict a structured step-by-step process.

Some example instances when a flowchart would be beneficial:

• Document the “as-is” or “to-be” business processes.

• Depict the logical flow of an algorithm which needs to be implemented.

• Show how a user can interact with a system to achieve a desired objective.

• Define the workflow for a given manual activity.

Alternative to Flowcharts

Since the advent of the flowchart, new modeling techniques and standards have been created and which, in many cases, have become more popular than the flowcharts, such as:

• Data Flow Diagram

• UML Activity Diagram

• BPMN Process Flow Diagram

• etc.

Example Flowchart