1. Use Case Definition: A use case describes in narrative prose
usually structured
the sequence of events
actions, transactions, ...
of an actor
human role, external computer systems, …
using a system
buying, ordering, managing information
to complete a process

2. Use Case: Example Example:
“Borrow Library Resources”
Patron arrives with the resources (books, videos, etc.) to borrow and submits them to the Librarian along with his/her library card
The librarian records the identification information on the card and the system validates the card [Exception: card not valid, overdue books, etc.]
For each resource, the Librarian records the call number.
Patron is told about the due dates
Patron leaves with the resources
Exceptions:
Card not valid: Patron is asked to get a valid card and resources are put back on the shelves
Overdue Books: Patron is asked to pay the dues in full (Collect Fines use case) before the Borrow transaction can proceed.
For more sample use cases and how to document a use case:
see