Workflow can be defined in many ways; however, one particular definition that illustrates how it applies is as follows: 

"Workflow describes an automated method of performing daily or routine tasks". 

These tasks can range from automatically generating an email, to issuing a message that tells the user to complete a specific screen and then taking the user to that particular screen to complete. Workflow allows users to communicate (via the linking of screens), set values and stop transactions from taking place. It is internally driven and deployed when key events, such as the hiring or termination of an employee, occur.