When a person chooses an item to borrow and presents their library card to the library, they take responsibility for the borrowed item and promise to abide by certain rules, usually including a promise to return the item by the due date or face a library fine.
If the cardholder violates these responsibilities, their borrowing privileges may be suspended.
When a patron borrowed a book, their name and the book's due date would be recorded on the borrowing card, which would be filed under the patron's name or card number.
The borrowing card would be replaced with a stamped due date card to inform the patron of the item's due date.
When the book was returned, the patron's name would be crossed off the borrowing card.