No single library, however large, can own every book, journal, or report its users might need. A student in a small-town college might need a research paper held only in a metropolitan university, while a researcher might require a rare manuscript located thousands of kilometres away. Interlibrary cooperation solves this gap. It allows one library to borrow materials on behalf of its users from another library, turning a collection of separate institutions into a connected web of shared knowledge. This post explains how interlibrary loan works, the role of the union catalogue, the benefits of resource sharing, and how photocopying and digital delivery transformed the entire system.
Table of Contents
- What interlibrary cooperation means
- The terms you will encounter
- How interlibrary loan systems evolved
- From posting parcels to electronic delivery
- The role of the union catalogue
- Union catalogues in practice
- The benefits of interlibrary cooperation
- Wider access without owning everything
- Reduced duplication and lower costs
- Stronger collaboration between institutions
- Support for research and learning
- How photocopying and document delivery modernised interlibrary loans
- From photocopies to scanned digital delivery
- The copyright dimension
- Bringing it together
What interlibrary cooperation means
Interlibrary loan, often shortened to ILL, is a service that lets the users of one library borrow materials held by another library. The process is straightforward in principle. When a user requests an item the home library does not own, the borrowing library identifies another library that holds it. The lending library then delivers the item, either physically or electronically, and the borrowing library passes it to the user and arranges for its return if needed.
This cooperation rests on a simple agreement: libraries help each other because no institution can be self-sufficient. A library that lends generously today becomes a borrower tomorrow. Over time, this mutual exchange builds a system where smaller libraries can offer their users a far richer range of materials than their own budgets would allow, while larger libraries share their depth of resources across the network. The result is a balanced arrangement that benefits institutions of every size.
The terms you will encounter
Interlibrary loan goes by several names depending on context. Document delivery usually refers to supplying copies of articles or book chapters rather than lending whole volumes. Resource sharing is the broader umbrella covering all forms of cooperative access. Inter-lending and document supply appear frequently in international literature. These terms overlap heavily, and many libraries use them interchangeably, but the underlying idea is always the same: extending access beyond the walls of a single collection.
How interlibrary loan systems evolved
The earliest form of cooperation involved physically lending books between libraries through the postal system. This worked, but it was slow, costly, and risky. A printed book had to be packaged, mailed, tracked, and eventually returned. If it was damaged or lost in transit, the borrowing library had to replace it. For a single article buried inside a thick bound journal, lending the entire volume was wasteful and impractical.
The arrival of the photocopying machine changed everything. As one scholarly account of document delivery notes, the shift from “interlibrary loan” to “document delivery” was driven almost entirely by photocopying technology, because copies could be supplied far more cheaply and efficiently than lending an item. Instead of mailing a whole journal volume, a library could photocopy the requested article and send only those few pages. This meant the lending library kept its original on the shelf while the user still received the content they needed.
A second major shift came from online bibliographic databases. These systems allowed users to identify materials at the article level rather than the whole-volume level, so requests became more precise. Over the following decades, fast image scanners, document transmission software, and dedicated ILL management systems pushed the service further. By the early part of this century, these automation technologies had been widely adopted by libraries of all types around the world.
From posting parcels to electronic delivery
The trajectory is clear: from mailing fragile parcels, to photocopying pages, to scanning and emailing digital files directly to a researcher’s desktop. The Library of Congress captured this transformation neatly with the motto of its scanning service, “Copy Once, Access Always.” Once a fragile or frequently requested item is scanned and linked to its catalogue record, the library can respond to future requests instantly without handling the original again. This protects rare materials while speeding up service.
The role of the union catalogue
Before a library can borrow an item, it must first know which library holds it. This is where the union catalogue becomes essential. A union catalogue is a single, combined database that lists the holdings of many libraries together. Instead of searching each library’s catalogue one by one, a librarian or user searches one shared database and instantly sees which institutions own the material they want.
The union catalogue does the heavy lifting of resource sharing. It consolidates bibliographic records from multiple libraries, allowing users to identify and locate materials across institutional boundaries. Without it, interlibrary loan would be a matter of guesswork and endless phone calls. With it, the entire process becomes a structured, searchable workflow.
Union catalogues in practice
India offers strong examples of how union catalogues power resource sharing. The Information and Library Network, known as INFLIBNET, was set up as a major programme of the University Grants Commission in 1991. Its union catalogue, IndCat, brings together the holdings of university libraries across the country. Beyond being a combined catalogue of books, IndCat also functions as a virtual catalogue for each participating library, and it includes specialised databases such as a union catalogue of theses and dissertations.
The Developing Library Network, or DELNET, provides another major example. Established in 1988, it began by networking libraries in Delhi before expanding nationally and internationally. DELNET maintains a wide range of union catalogues, including a union catalogue of books, a union list of current periodicals, a union catalogue of periodicals, a database of periodical articles, and a database of theses and dissertations. These catalogues collectively form one of the largest bibliographic resources in the country, with the book database alone holding tens of millions of records.
The benefits of interlibrary cooperation
Resource sharing delivers practical advantages that no individual library can achieve alone. These benefits explain why libraries invest time and money in cooperative networks.
Wider access without owning everything
The most obvious benefit is expanded access. A library cannot purchase every book and subscribe to every journal, and budgets are always limited. Through cooperation, users gain access to a vast pool of materials held across many institutions. A study of resource sharing among Indian universities through INFLIBNET described how such a network provides a common platform for libraries to come together, communicate, and help one another meet user demands. This is particularly valuable for rare, expensive, or hard-to-find materials that a single library would rarely justify purchasing.
Reduced duplication and lower costs
When libraries share resources, they avoid buying the same expensive items repeatedly. If one library in a network already owns a costly reference work or specialised journal, others can borrow it rather than purchasing their own copies. INFLIBNET’s resource sharing model is explicitly designed to reduce the cost and effort of acquiring new materials by letting users borrow from other libraries. This frees up funds that libraries can redirect toward materials their users need most.
Stronger collaboration between institutions
Cooperation also builds professional relationships and shared expertise. Networks like DELNET provide technical assistance to member libraries for cataloguing, serials control, union catalogue preparation, and interlibrary loan itself. Smaller libraries gain access to systems and knowledge they could not develop alone, while larger libraries benefit from being part of a wider, well-organised community. Over time, this collaboration raises the standard of library service across the entire network.
Support for research and learning
For students and researchers, the benefits are direct. A union catalogue of theses prevents duplication of research by showing what has already been studied, while access to journal articles from distant libraries supports literature reviews and original work. In the Indian academic context, the establishment of INFLIBNET marked a turning point because it connected university libraries across the country and transformed the scale and speed of cooperation, enabling real-time resource discovery.
How photocopying and document delivery modernised interlibrary loans
Photocopying deserves special attention because it fundamentally reshaped interlibrary cooperation. Before photocopiers, supplying a single article meant lending an entire bound journal, which was slow and exposed the original to damage. Photocopying allowed libraries to duplicate documents quickly and cheaply, supplying just the needed pages while keeping the source material safe on the shelf.
This shift gave rise to an entire document supply industry. Requests moved from whole volumes to individual articles, and the speed of service improved dramatically. In the Indian context, networks built photocopying directly into their cooperation models. DELNET, for example, provides the delivery of individual books along with photocopies of articles published in India and abroad through its interlibrary loan and document delivery services.
From photocopies to scanned digital delivery
Photocopying was only the beginning. As scanning technology matured, libraries began converting photocopied pages into digital files that could be transmitted electronically. The advantages were significant. The early pioneers of interlibrary loan digitization in the 1990s had to adapt commercial scanning equipment, since no scanners were made specifically for library digitization at the time. Once dedicated systems and document transmission software appeared, articles could be scanned and delivered far faster than any postal copy.
Today many academic libraries scan articles and book chapters and deliver them straight to a user’s desktop. A typical university service now lets users request a book, ask for a photocopy of an article or book chapter, and have copies scanned and delivered electronically. This is the modern face of document delivery: fast, precise, and increasingly digital, while still resting on the same cooperative principle that has always defined interlibrary loan.
The copyright dimension
Photocopying and scanning operate within copyright law, and libraries take this seriously. Copying for interlibrary loan is generally permitted for private study, scholarship, or research, but using copies beyond these purposes can amount to infringement. Many libraries display copyright notices and ask users to conduct a fair use analysis where appropriate, as the copyright law governs the making of photocopies or other reproductions of protected material. Responsible cooperation therefore balances access with respect for the rights of authors and publishers.
Bringing it together
Interlibrary cooperation turns isolated collections into a shared resource far greater than any single library. The union catalogue makes materials discoverable, interlibrary loan makes them accessible, and photocopying and digital delivery make that access fast and efficient. Networks like INFLIBNET and DELNET show how this works at national scale, connecting thousands of institutions and giving students and researchers reach far beyond their local shelves. As collections continue to move online, the core idea remains unchanged: libraries serve their users best when they work together.
What do you think? If your nearest library could instantly borrow from any institution in the country, how would that change the way you research and study? And as digital delivery replaces physical lending, what should libraries do to keep rare and fragile materials accessible while protecting them for future generations?
References
- https://en.wikipedia.org/wiki/Interlibrary_loan
- https://docs.lib.purdue.edu/iatul/1989/papers/3
- https://www.sciencedirect.com/topics/computer-science/interlibrary-loan
- https://www.loc.gov/item/prn-00-161
- https://ebooks.inflibnet.ac.in/lisp5/chapter/library-networks-in-india-case-study-inflibnet/
- https://ebooks.inflibnet.ac.in/lisp12/chapter/research-library-networks-consortia-and-resource-sharing/
- https://www.tandfonline.com/doi/abs/10.1080/1072303X.2016.1218400
- https://srec.ac.in/facilities/resourcesharing
- https://www.imageaccess.com/bscan-ill
- https://www.lib.uiowa.edu/services/illdd/
- https://library.charlotte.edu/check-out-request/request-items/interlibrary-loan-document-delivery

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