Link+

Interlibrary loan (abbreviated ILL, and sometimes called interloan, interlending, document delivery, or document supply) is a service whereby a patron of one library can borrow books, DVDs, music, etc. and/or receive photocopies of documents that are owned by another library. The user makes a request with their home library; which, acting as an intermediary, identifies libraries with the desired item, places the request, receives the item, makes it available to the user, as well as arranges for its return. The lending library usually sets a due date and overdue fees of the material borrowed. Although books and journal articles are the most frequently requested items, some libraries will lend audio recordings, video recordings, maps, sheet music, and microforms of all kinds. In some cases, nominal fees accompany the interlibrary loan services.

The term document delivery may also be used for a related service, namely the supply of journal articles and other copies on a personalized basis, whether these come from other libraries or direct from the publishers. The end user is usually responsible for any fees, such as costs for postage or photocopying. Commercial document delivery services will borrow on behalf of any customer willing to pay for their rates.

Interlibrary loan, or resource sharing, has two operations: borrowing and lending.

Interlibrary loan and resource sharing have a variety of systems and workflows, often based on the scale of service, regional networks, and library systems. Processes are automated by computer systems such as VDX based on ISO ILL standards 10161 and 10160. Two major systems are used heavily: ILLiad developed by Atlas Systems and Worldshare Management System by OCLC. In 2017, OCLC announced a new interlibrary loan management system called Tipasa, which is built on the OCLC WorldShare technology platform, and is the first entirely cloud-based interlibrary loan management system.

Loan requests between branch libraries in the same local library system are usually filled promptly, while loan requests between library systems may take weeks to complete. However, if an item is rare, fragile, or exceptionally valuable, the owning library is under no obligation to release it for interlibrary loan. Some collections and volumes, especially bound journals and one-of-a-kind manuscripts, are non-circulating, meaning that they may not be borrowed. Books may be delivered by mail or by courier service. Photocopies may be faxed, or scanned and delivered electronically. Urgent requests are placed if the item is needed right away; sometimes for additional fees. Public libraries do not usually offer urgent service.

...
Wikipedia