For the staff, ILL gives them the ability to track both borrowing and lending functions for their library. The location of each book loaned, the billing status of loaned items, and requests pending for materials are all handled within ILL.

ILL allows the borrowing library to send a lending library a request to borrow, photocopy, or scan materials for use by their requestor. On the other side of the transaction, the lending library fills the request by sending materials to the borrowing libraries.

ILL makes finding materials a smooth process, for both the borrowing libraries and the lending libraries. By accessing additional catalogs, patrons can source materials they would not find in their own libraries. ILL is especially useful when Loans requests between branch libraries in the same system may be filled in a brief amount of time, while loan requests between library systems may take weeks or more to be delivered. If an item is rare or difficult to find, this may be the easiest way to gain access to it. However, if an item is rare or difficult to find, interlibrary loan does not guarantee that the lending library will send the item to you through your local library. Some collections and volumes may be non-circulating.

Libraries have formed voluntary associations with each other to provide an online union catalog of all the items held by all member libraries. Whenever a library adds a new item to its catalog, a copy of the record is sent to update the union list. This allows libraries to quickly find out what other libraries hold an item, and the software can facilitate the requesting and supplying of interlibrary loans.