When a patron wants to borrow an item, they present the item to a librarian, who scans the barcode using a barcode scanner. The scanner reads the barcode and sends the item's unique identifier to the library's database. The database retrieves information about the item, such as its title and circulation status, and displays this information on the librarian's computer screen. If the item is available, the librarian checks it out to the patron and updates the database accordingly. If the item is not available, the librarian may place a hold on the item for the patron.
When the patron returns the item, the barcode is scanned again using a barcode scanner. The scanner sends the item's unique identifier to the library's database, which updates the item's circulation status and returns it to the collection.