A digital library is a library in which collections are stored in digital formats (as opposed to print, microform, or other media) and accessible by computers. The digital content may be stored locally, or accessed remotely via computer networks. A digital library is a type of information retrieval system.
Libraries have exemplified the public realm by fulfilling the constitutional interest in the promotion of learning and invention. Today, a debate about the future shape of the public interest in learning is tacit within the concept of a digital library, not only in legislative deliberations about the form that intellectual property should take in the information age, but in the absence of legislative interest in a national digital library.
In the early 1950s computers entered library services in the form of punched card applications in technical services operations and through the development of the MARC (MAchine-Readable Cataloging) standard for digitizing and communicating library catalog information (Harter, 1997). The vision of a fully computer-based library began to emerge in terminology in the mid-60s with J. C. R. Licklider's the library of the future. Over the years, other terms have been coined to refer to the concept of a digitized library, including electronic library, virtual library, library without walls, and bionic library, (Harter, 1997).
From the start, librarians and other information specialists played a part in the birth of the digital library concept. In 1990, the Coalition for Networked Information (CNI) was formed to coordinate the networking of information sources used and created by educators, librarians, information technology professionals, government agencies, and commercial vendors. One of CNI's goals was to "put a 'virtual library' into scholars' hands, giving them access to all information available electronically.
Some models of the digital library involve image scanning of printed material, particularly for retrospective conversion; others involve ASCII-based text. In principle, much of the image-scanned material can be converted through OCR, and such projects as JSTOR do this; but there are still other materials which are provided as images and which may be hard to search. With time, though, the advent of standards will decrease the various conversion problems that plague us today.
Digital libraries are complex and advanced forms of information systems that can be endowed with a multiplicity of functions and features. These can include collaboration support, distributed database management, hypertext, multimedia information services, information retrieval, information filtering, selective dissemination of information, intellectual property rights management, question answering and reference services, and resource discovery, among many others. Digital libraries can serve very large user populations that are composed of different stakeholder groups with different information needs.
There is no doubt that the future success of libraries depends on their ability to change and evolve to meet the changing ways that people access and use information. As director of the Institute of Museums and Library Services, the federal voice for library and museum service in the U.S. – I see three big goals for libraries: provide engaging learning experiences, become community anchors, and provide access to content even as the devices for accessing that content change rapidly.
It's sometimes felt lately that elements of the publishing and consumer electronics worlds have wanted to hit a big "reset" button on that great American project of Andrew Carnegie: the public library. So it's somewhat reassuring to hear Peter Baldwin, chair of the Arcadia Fund, say "What Carnegie did for public libraries a century ago, the DPLA [Digital Public Library Association] could – if successful – accomplish for our era." The Arcadia Fund, along with the Sloan Foundation, announced $5 million funding today to help the initiative move forward.
The vision of a national digital library has been circulating among librarians, scholars, educators, and private industry representatives since the early 1990s, but it has not yet materialized. Efforts led by a range of organizations, including the Library of Congress, HathiTrust, and the Internet Archive, have successfully built resources that provide books, images, historical records, and audiovisual materials to anyone with Internet access. Many libraries have digitized materials, but still, no project has yet succeeded in bringing these different viewpoints, experiences, and collections together with leading technical experts and the best of private industry to find solutions to these complex challenges.
Lynch (2003) argues that the future of digital libraries lies not in supporting generic, broadly useful services such as information access to large collections and knowledge stores, but in supporting "customization by community", i.e. the development of services tailored to support the specific, and real, practices of different user constituencies. Similarly, Borgman (1999) defines digital libraries as being constructed by and for a community of users, with functionalities specifically designed to support their particular information needs.
The challenges of building an online library are the those of building any library in an era of superabundant information. Questions like, "How do you make collections findable and usable?" get harder to pin down as the amount of material increases. Digital preservation has become the watchword now, but some of the fundamental challenges that confront libraries have always been with them: how to manage ever-bigger amounts of information and how to make best collective use of resources.