Actors are not part of the system—they represent anyone or anything that must interact with the system. An actor may
Only input information to the system
Only receive information from the system
Input and receive information to and from the system
Typically, these actors are found in the problem statement and by conversations with customers and domain experts. The following questions may be used to help identify the actors for a system:
Who is interested in a certain requirement?
Where in the organization is the system used?
Who will benefit from the use of the system?
Who will supply the system with this information, use this information, and remove this information?
Who will support and maintain the system?
Does the system use an external resource? ...