Digital library

A digital library is an online database of digital resources that can include text, still images, audio, video, digital documents, or other digital media formats or a library accessible through the internet. Objects can consist of digitized content like print or photographs, as well as originally produced digital content like word processor files or social media posts. In addition to storing content, digital libraries provide means for organizing, searching, and retrieving the content contained in the collection. Digital libraries can vary immensely in size and scope, and can be maintained by individuals or organizations. The digital content may be stored locally, or accessed remotely via computer networks. These information retrieval systems are able to exchange information with each other through interoperability and sustainability.

History

The early history of digital libraries is not well documented, but several key thinkers are connected to the emergence of the concept. Predecessors include Paul Otlet and Henri La Fontaine's Mundaneum, an attempt begun in 1895 to gather and systematically catalogue the world's knowledge, with the hope of bringing about world peace. The visions of the digital library were largely realized a century later during the great expansion of the Internet.
Vannevar Bush and J. C. R. Licklider are two contributors that advanced this idea into then current technology. Bush had supported research that led to the bomb that was dropped on Hiroshima. After seeing the city's destruction, he wanted to create a machine that would show how technology can lead to understanding instead of destruction. This machine would include a desk with two screens, switches and buttons, and a keyboard. He named this the "Memex". This way individuals would be able to access stored books and files at a rapid speed. In 1956, Ford Foundation funded Licklider to analyze how libraries could be improved with technology. Almost a decade later, his book entitled "Libraries of the Future" included his vision. He wanted to create a system that would use computers and networks so human knowledge would be accessible for human needs and feedback would be automatic for machine purposes. This system contained three components, the corpus of knowledge, the question, and the answer. Licklider called it a procognitive system.
In 1980, the role of the library in an electronic society was the focus of a clinic on library applications of data processing. Participants included Frederick Wilfrid Lancaster, Derek De Solla Price, Gerard Salton, and Michael Gorman).
Early projects centered on the creation of an electronic card catalogue known as Online Public Access Catalog. By the 1980s, the success of these endeavors resulted in OPAC replacing the traditional card catalog in many academic, public and special libraries. This permitted libraries to undertake additional rewarding co-operative efforts to support resource sharing and expand access to library materials beyond an individual library.
An early example of a digital library is the Education Resources Information Center, a database of education citations, abstracts and texts that was created in 1964 and made available online through DIALOG in 1969.
In 1994, digital libraries became widely visible in the research community due to a $24.4 million NSF managed program supported jointly by DARPA's Intelligent Integration of Information program, NASA, and NSF itself. Successful research proposals came from six U.S. universities. The universities included Carnegie Mellon University, University of California-Berkeley, University of Michigan, University of Illinois, University of California-Santa Barbara, and Stanford University. Articles from the projects summarized their progress at their halfway point in May 1996. Stanford research, by Sergey Brin and Larry Page, led to the founding of Google.
Early attempts at creating a model for digital libraries included the DELOS Digital Library Reference Model and the 5S Framework.

Terminology

The term digital library was first popularized by the NSF/DARPA/NASA Digital Libraries Initiative in 1994. With the availability of the computer networks the information resources are expected to stay distributed and accessed as needed, whereas in Vannevar Bush's essay As We May Think they were to be collected and kept within the researcher's Memex.
The term virtual library was initially used interchangeably with digital library, but is now primarily used for libraries that are virtual in other senses. In the early days of digital libraries, there was discussion of the similarities and differences among the terms digital, virtual, and electronic.
A distinction is often made between content that was created in a digital format, known as born-digital, and information that has been converted from a physical medium, e.g. paper, through digitization. Not all electronic content is in digital data format. The term hybrid library is sometimes used for libraries that have both physical collections and electronic collections. For example, American Memory is a digital library within the Library of Congress.
Some important digital libraries also serve as long term archives, such as arXiv and the Internet Archive. Others, such as the Digital Public Library of America, seek to make digital information from various institutions widely accessible online.

Types of digital libraries

Institutional repositories

Many academic libraries are actively involved in building repositories of their institution's books, papers, theses, and other works that can be digitized or were 'born digital'. Many of these repositories are made available to the general public with few restrictions, in accordance with the goals of open access, in contrast to the publication of research in commercial journals, where the publishers usually limit access rights. Irrespective of access rights, institutional, truly free, and corporate repositories can be referred to as digital libraries. Institutional repository software is designed for archiving, organizing, and searching a library's content. Popular open-source solutions include DSpace, Greenstone Digital Library, EPrints, Digital Commons, and the Fedora Commons-based systems Islandora and Samvera.

National library collections

is often covered by copyright legislation and sometimes by laws specific to legal deposit, and requires that one or more copies of all material published in a country should be submitted for preservation in an institution, typically the national library. Since the advent of electronic documents, legislation has had to be amended to cover the new formats, such as the 2016 amendment to the Copyright Act 1968 in Australia.
Since then various types of electronic depositories have been built. The British Library's Publisher Submission Portal and the German model at the Deutsche Nationalbibliothek have one deposit point for a network of libraries, but public access is only available in the reading rooms in the libraries. The Australian National edeposit system has the same features, but also allows for remote access by the general public for most of the content.

Digital archives

Physical archives differ from physical libraries in several ways. Traditionally, archives are defined as:

Containing primary sources of information rather than the secondary sources found in a library.
Having their contents organized in groups rather than individual items.
Having unique contents.

The technology used to create digital libraries is even more revolutionary for archives since it breaks down the second and third of these general rules. In other words, "digital archives" or "online archives" will still generally contain primary sources, but they are likely to be described individually rather than in groups or collections. Further, because they are digital, their contents are easily reproducible and may indeed have been reproduced from elsewhere. The Oxford Text Archive is generally considered to be the oldest digital archive of academic physical primary source materials.
Archives differ from libraries in the nature of the materials held. Libraries collect individual published books and serials, or bounded sets of individual items. The books and journals held by libraries are not unique, since multiple copies exist and any given copy will generally prove as satisfactory as any other copy. The material in archives and manuscript libraries are "the unique records of corporate bodies and the papers of individuals and families".
A fundamental characteristic of archives is that they have to keep the context in which their records have been created and the network of relationships between them in order to preserve their informative content and provide understandable and useful information over time. The fundamental characteristic of archives resides in their hierarchical organization expressing the context by means of the archival bond.
Archival descriptions are the fundamental means to describe, understand, retrieve and access archival material. At the digital level, archival descriptions are usually encoded by means of the Encoded Archival Description XML format. The EAD is a standardized electronic representation of archival description which makes it possible to provide union access to detailed archival descriptions and resources in repositories distributed throughout the world.
Given the importance of archives, a dedicated formal model, called NEsted SeTs for Object Hierarchies, built around their peculiar constituents, has been defined. NESTOR is based on the idea of expressing the hierarchical relationships between objects through the inclusion property between sets, in contrast to the binary relation between nodes exploited by the tree. NESTOR has been used to formally extend the 5S model to define a digital archive as a specific case of digital library able to take into consideration the peculiar features of archives.