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A digital library, also called an online library, an internet library, a digital repository, or a digital collection is an
online database An online database is a database accessible from a local network or the Internet, as opposed to one that is stored locally on an individual computer or its attached storage (such as a CD). Online databases are hosted on websites, made available as ...
of digital objects that can include text, still images, audio, video, digital documents, or other
digital media Digital media is any communication media that operate in conjunction with various encoded machine-readable data formats. Digital media can be created, viewed, distributed, modified, listened to, and preserved on a digital electronics device. ...
formats or a
library A library is a collection of materials, books or media that are accessible for use and not just for display purposes. A library provides physical (hard copies) or digital access (soft copies) materials, and may be a physical location or a vi ...
accessible through the
internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, p ...
. Objects can consist of
digitized DigitizationTech Target. (2011, April). Definition: digitization. ''WhatIs.com''. Retrieved December 15, 2021, from https://whatis.techtarget.com/definition/digitization is the process of converting information into a Digital data, digital (i ...
content like print or
photographs A photograph (also known as a photo, image, or picture) is an image created by light falling on a photosensitive surface, usually photographic film or an electronic image sensor, such as a CCD or a CMOS chip. Most photographs are now created ...
, as well as originally produced digital content like
word processor A word processor (WP) is a device or computer program that provides for input, editing, formatting, and output of text, often with some additional features. Early word processors were stand-alone devices dedicated to the function, but current ...
files or
social media Social media are interactive media technologies that facilitate the creation and sharing of information, ideas, interests, and other forms of expression through virtual communities and networks. While challenges to the definition of ''social me ...
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 Interoperability is a characteristic of a product or system to work with other products or systems. While the term was initially defined for information technology or systems engineering services to allow for information exchange, a broader defi ...
and
sustainability Specific definitions of sustainability are difficult to agree on and have varied in the literature and over time. The concept of sustainability can be used to guide decisions at the global, national, and individual levels (e.g. sustainable livi ...
.


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 Paul Marie Ghislain Otlet (; ; 23 August 1868 – 10 December 1944) was a Belgian author, entrepreneur, lawyer and peace activist; predicting the arrival of the internet before World War II, he is among those considered to be the father of infor ...
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, with access to the books and searching of the documents by millions of individuals on the World Wide Web.
Vannevar Bush Vannevar Bush ( ; March 11, 1890 – June 28, 1974) was an American engineer, inventor and science administrator, who during World War II headed the U.S. Office of Scientific Research and Development (OSRD), through which almost all warti ...
and
J.C.R. Licklider Joseph Carl Robnett Licklider (; March 11, 1915 – June 26, 1990), known simply as J. C. R. or "Lick", was an American psychologistMiller, G. A. (1991), "J. C. R. Licklider, psychologist", ''Journal of the Acoustical Society of A ...
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 is the capital of Hiroshima Prefecture in Japan. , the city had an estimated population of 1,199,391. The gross domestic product (GDP) in Greater Hiroshima, Hiroshima Urban Employment Area, was US$61.3 billion as of 2010. Kazumi Matsui ...
. After seeing the disaster, 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 The Ford Foundation is an American private foundation with the stated goal of advancing human welfare. Created in 1936 by Edsel Ford and his father Henry Ford, it was originally funded by a US$25,000 gift from Edsel Ford. By 1947, after the death ...
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. Early projects centered on the creation of an electronic card catalogue known as Online Public Access Catalog (OPAC). 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 (ERIC), 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 The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the A ...
's Intelligent Integration of Information (I3) program,
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...
, and NSF itself. Successful research proposals came from six U.S. universities. The universities included
Carnegie Mellon University Carnegie Mellon University (CMU) is a private research university in Pittsburgh, Pennsylvania. One of its predecessors was established in 1900 by Andrew Carnegie as the Carnegie Technical Schools; it became the Carnegie Institute of Technology ...
,
University of California-Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...
,
University of Michigan , mottoeng = "Arts, Knowledge, Truth" , former_names = Catholepistemiad, or University of Michigania (1817–1821) , budget = $10.3 billion (2021) , endowment = $17 billion (2021)As o ...
,
University of Illinois The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the Uni ...
, University of California-Santa Barbara, and
Stanford University Stanford University, officially Leland Stanford Junior University, is a private research university in Stanford, California. The campus occupies , among the largest in the United States, and enrolls over 17,000 students. Stanford is conside ...
. Articles from the projects summarized their progress at their halfway point in May 1996. Stanford research, by
Sergey Brin Sergey Mikhailovich Brin (russian: link=no, Сергей Михайлович Брин; born August 21, 1973) is an American business magnate, computer scientist, and internet entrepreneur, who co-founded Google with Larry Page. Brin was th ...
and Larry Page, led to the founding of
Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...
. Early attempts at creating a model for digital libraries included the DELOS ''Digital Library Reference Model''L. Candela et al.: ''The DELOS Digital Library Reference Model: Foundations for Digital Libraries''. Version 0.98, February 2008
PDF
)
and the 5S Framework.


Terminology

The term ''digital library'' was first popularized by the NSF/
DARPA The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the A ...
/
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...
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 Vannevar Bush ( ; March 11, 1890 – June 28, 1974) was an American engineer, inventor and science administrator, who during World War II headed the U.S. Office of Scientific Research and Development (OSRD), through which almost all warti ...
's essay ''
As We May Think "As We May Think" is a 1945 essay by Vannevar Bush which has been described as visionary and influential, anticipating many aspects of information society. It was first published in ''The Atlantic'' in July 1945 and republished in an abridged ...
'' (1945) 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 (such as libraries which aggregate distributed content). 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 The term born-digital refers to materials that originate in a digital form.NDIIPP"Preserving Digital Culture,"Library of Congress. This is in contrast to digital reformatting, through which analog materials become digital, as in the case of file ...
, and information that has been converted from a physical medium, e.g. paper, through
digitization DigitizationTech Target. (2011, April). Definition: digitization. ''WhatIs.com''. Retrieved December 15, 2021, from https://whatis.techtarget.com/definition/digitization is the process of converting information into a digital (i.e. computer-r ...
. Not all electronic content is in
digital data Digital data, in information theory and information systems, is information represented as a string of discrete symbols each of which can take on one of only a finite number of values from some alphabet, such as letters or digits. An exampl ...
format. The term hybrid library is sometimes used for libraries that have both physical collections and electronic collections. For example,
American Memory American Memory is an internet-based archive for public domain image resources, as well as audio, video, and archived Web content. Published by the Library of Congress, the archive launched on October 13, 1994, after $13 million was raised in ...
is a digital library within the
Library of Congress The Library of Congress (LOC) is the research library that officially serves the United States Congress and is the ''de facto'' national library of the United States. It is the oldest federal cultural institution in the country. The libra ...
. Some important digital libraries also serve as long term archives, such as
arXiv arXiv (pronounced "archive"—the X represents the Greek letter chi ⟨χ⟩) is an open-access repository of electronic preprints and postprints (known as e-prints) approved for posting after moderation, but not peer review. It consists of ...
and the
Internet Archive The Internet Archive is an American digital library with the stated mission of "universal access to all knowledge". It provides free public access to collections of digitized materials, including websites, software applications/games, music, ...
. 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 Open access (OA) is a set of principles and a range of practices through which research outputs are distributed online, free of access charges or other barriers. With open access strictly defined (according to the 2001 definition), or libre op ...
, 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 An institutional repository is an archive for collecting, preserving, and disseminating digital copies of the intellectual output of an institution, particularly a research institution. Academics also utilize their IRs for archiving published work ...
software is designed for archiving, organizing, and searching a library's content. Popular open-source solutions include
DSpace DSpace is an open source repository software package typically used for creating open access repositories for scholarly and/or published digital content. While DSpace shares some feature overlap with content management systems and document manag ...
, Greenstone Digital Library (GSDL),
EPrints EPrints is a free and open-source software package for building open access repositories that are compliant with the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH). It shares many of the features commonly seen in document ...
, Digital Commons, and the
Fedora Commons Fedora (or Flexible Extensible Digital Object Repository Architecture) is a digital asset management (DAM) content repository architecture upon which institutional repositories, digital archives, and digital library systems might be built. Fed ...
-based systems Islandora and
Samvera Samvera, originally known as Hydra, is an open-source digital repository software product. Samvera main components are Fedora Commons, Solr, Blacklight, and HydraHead (a Ruby on Rails plugin and gem, respectively). Each Samvera implementation is ...
.


National library collections

Legal deposit Legal deposit is a legal requirement that a person or group submit copies of their publications to a repository, usually a library. The number of copies required varies from country to country. Typically, the national library is the primary reposi ...
is often covered by
copyright A copyright is a type of intellectual property that gives its owner the exclusive right to copy, distribute, adapt, display, and perform a creative work, usually for a limited time. The creative work may be in a literary, artistic, educatio ...
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 A national library is a library established by a government as a country's preeminent repository of information. Unlike public libraries, these rarely allow citizens to borrow books. Often, they include numerous rare, valuable, or significant wo ...
. Since the advent of
electronic document An electronic document is any electronic media content (other than computer programs or system files) that is intended to be used in either an electronic form or as printed output. Originally, any computer data were considered as something inter ...
s, legislation has had to be amended to cover the new formats, such as the 2016 amendment to the ''
Copyright Act 1968 The copyright law of Australia defines the legally enforceable rights of creators of creative and artistic works under Australian law. The scope of copyright in Australia is defined in the '' Copyright Act 1968'' (as amended), which applies the ...
'' in Australia. Since then various types of electronic depositories have been built. The
British Library The British Library is the national library of the United Kingdom and is one of the largest libraries in the world. It is estimated to contain between 170 and 200 million items from many countries. As a legal deposit library, the Briti ...
's Publisher Submission Portal and the German model at the
Deutsche Nationalbibliothek The German National Library (DNB; german: Deutsche Nationalbibliothek) is the central archival library and national bibliographic centre for the Federal Republic of Germany. It is one of the largest libraries in the world. Its task is to colle ...
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 National edeposit (NED) is a collaboration between Australia's nine national, state and territory libraries which provides for the legal deposit, management, storage and preservation of, and access to, published electronic material across Aus ...
system has the same features, but also allows for remote access by the general public for most of the content.


Digital archives

Physical
archives An archive is an accumulation of historical records or materials – in any medium – or the physical facility in which they are located. Archives contain primary source documents that have accumulated over the course of an individual o ...
differ from physical libraries in several ways. Traditionally, archives are defined as: # Containing
primary source In the study of history as an academic discipline, a primary source (also called an original source) is an artifact, document, diary, manuscript, autobiography, recording, or any other source of information that was created at the time under ...
s of information (typically letters and papers directly produced by an individual or organization) rather than the secondary sources found in a library (books, periodicals, etc.). # 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 (or in addition to) 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 Oxford Text Archive (OTA) is an archive of electronic texts and other literary and language resources which have been created, collected and distributed for the purpose of research into literary and linguistic topics at the University of Oxford, E ...
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 The archival bond is a concept in archival theory referring to the relationship that each archival record has with the other records produced as part of the same transaction or activity and located within the same grouping. These bonds are a core co ...
. 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 Encoded Archival Description (EAD) is a standard for encoding descriptive information regarding archival records.Pitti, D (2012). "Encoded Archival Description (EAD)." In Bates, Marcia J., (ed.) ''Understanding Information Retrieval Systems: Managem ...
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 (NESTOR), 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.


Features of digital libraries

The advantages of digital libraries as a means of easily and rapidly accessing books, archives and images of various types are now widely recognized by commercial interests and public bodies alike. Traditional libraries are limited by storage space; digital libraries have the potential to store much more information, simply because digital information requires very little physical space to contain it. As such, the cost of maintaining a digital library can be much lower than that of a traditional library. A physical library must spend large sums of money paying for staff, book maintenance, rent, and additional books. Digital libraries may reduce or, in some instances, do away with these fees. Both types of library require cataloging input to allow users to locate and retrieve material. Digital libraries may be more willing to adopt innovations in technology providing users with improvements in electronic and audio book technology as well as presenting new forms of communication such as wikis and blogs; conventional libraries may consider that providing online access to their OP AC catalog is sufficient. An important advantage to digital conversion is increased accessibility to users. They also increase availability to individuals who may not be traditional patrons of a library, due to geographic location or organizational affiliation. * No physical boundary: The user of a digital library need not to go to the library physically; people from all over the world can gain access to the same information, as long as an Internet connection is available. * Round the clock availability: A major advantage of digital libraries is that people can gain access 24/7 to the information. * Multiple access: The same resources can be used simultaneously by a number of institutions and patrons. This may not be the case for copyrighted material: a library may have a license for "lending out" only one copy at a time; this is achieved with a system of
digital rights management Digital rights management (DRM) is the management of legal access to digital content. Various tools or technological protection measures (TPM) such as access control technologies can restrict the use of proprietary hardware and copyrighted work ...
where a resource can become inaccessible after expiration of the lending period or after the lender chooses to make it inaccessible (equivalent to returning the resource). * Information retrieval: The user is able to use any search term (word, phrase, title, name, subject) to search the entire collection. Digital libraries can provide very user-friendly interfaces, giving click able access to its resources. * Preservation and conservation: Digitization is not a long-term preservation solution for physical collections, but does succeed in providing access copies for materials that would otherwise fall to degradation from repeated use. Digitized collections and born-digital objects pose many preservation and conservation concerns that analog materials do not. Please see the following "Problems" section of this page for examples. * Space: Whereas traditional libraries are limited by storage space, digital libraries have the potential to store much more information, simply because digital information requires very little physical space to contain them and media storage technologies are more affordable than ever before. * Added value: Certain characteristics of objects, primarily the quality of images, may be improved. Digitization can enhance legibility and remove visible flaws such as stains and discoloration.


Software

There are a number of software packages for use in general digital libraries (for notable ones see :Digital library software). Institutional repository software, which focuses primarily on ingest, preservation and access of locally produced documents, particularly locally produced academic outputs, can be found in
Institutional repository software Institutions are humanly devised structures of rules and norms that shape and constrain individual behavior. All definitions of institutions generally entail that there is a level of persistence and continuity. Laws, rules, social conventions a ...
. This software may be proprietary, as is the case with the Library of Congress which uses Digiboard and CTS to manage digital content. The design and implementation in digital libraries are constructed so computer systems and software can make use of the information when it is exchanged. These are referred to as semantic digital libraries. Semantic libraries are also used to socialize with different communities from a mass of social networks. DjDL is a type of semantic digital library. Keywords-based and semantic search are the two main types of searches. A tool is provided in the semantic search that create a group for augmentation and refinement for keywords-based search. Conceptual knowledge used in DjDL is centered around two forms; the subject
ontology In metaphysics, ontology is the philosophy, philosophical study of being, as well as related concepts such as existence, Becoming (philosophy), becoming, and reality. Ontology addresses questions like how entities are grouped into Category ...
and the set of concept search patterns based on the ontology. The three type of ontologies that are associated to this search are bibliographic ontologies, community-aware ontologies, and subject ontologies.


Metadata

In traditional libraries, the ability to find works of interest is directly related to how well they were cataloged. While cataloging electronic works digitized from a library's existing holding may be as simple as copying or moving a record from the print to the electronic form, complex and born-digital works require substantially more effort. To handle the growing volume of electronic publications, new tools and technologies have to be designed to allow effective automated semantic classification and searching. While full-text search can be used for some items, there are many common catalog searches which cannot be performed using full text, including: * finding texts which are translations of other texts * differentiating between editions/volumes of a text/periodical * inconsistent descriptors (especially subject headings) * missing, deficient or poor quality
taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
practices * linking texts published under pseudonyms to the real authors (
Samuel Clemens Samuel Langhorne Clemens (November 30, 1835 – April 21, 1910), known by his pen name Mark Twain, was an American writer, humorist, entrepreneur, publisher, and lecturer. He was praised as the "greatest humorist the United States has p ...
and
Mark Twain Samuel Langhorne Clemens (November 30, 1835 – April 21, 1910), known by his pen name Mark Twain, was an American writer, humorist, entrepreneur, publisher, and lecturer. He was praised as the "greatest humorist the United States has pr ...
, for example) * differentiating non-fiction from parody (''
The Onion ''The Onion'' is an American digital media company and newspaper organization that publishes satire, satirical articles on international, national, and local news. The company is based in Chicago but originated as a weekly print publication on ...
'' from ''
The New York Times ''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...
'')


Searching

Most digital libraries provide a search interface which allows resources to be found. These resources are typically
deep web The deep web, invisible web, or hidden web are parts of the World Wide Web whose contents are not indexed by standard web search-engine programs. This is in contrast to the "surface web", which is accessible to anyone using the Internet. Co ...
(or invisible web) resources since they frequently cannot be located by
search engine A search engine is a software system designed to carry out web searches. They search the World Wide Web in a systematic way for particular information specified in a textual web search query. The search results are generally presented in a ...
crawlers. Some digital libraries create special pages or sitemaps to allow search engines to find all their resources. Digital libraries frequently use the
Open Archives Initiative Protocol for Metadata Harvesting The Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) is a protocol developed for harvesting metadata descriptions of records in an archive so that services can be built using metadata from many archives. An implementation of O ...
(OAI-PMH) to expose their metadata to other digital libraries, and search engines like
Google Scholar Google Scholar is a freely accessible web search engine that indexes the full text or metadata of scholarly literature across an array of publishing formats and disciplines. Released in beta in November 2004, the Google Scholar index includes ...
,
Yahoo! Yahoo! (, styled yahoo''!'' in its logo) is an American web services provider. It is headquartered in Sunnyvale, California and operated by the namesake company Yahoo Inc., which is 90% owned by investment funds managed by Apollo Global Mana ...
and Scirus can also use OAI-PMH to find these deep web resources. There are two general strategies for searching a ''federation'' of digital libraries: distributed searching and searching previously harvested
metadata Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the descriptive ...
. Distributed searching typically involves a client sending multiple search requests in parallel to a number of servers in the federation. The results are gathered, duplicates are eliminated or clustered, and the remaining items are sorted and presented back to the client. Protocols like
Z39.50 Z39.50 is an international standard client–server, application layer communications protocol for searching and retrieving information from a database over a TCP/IP computer network, developed and maintained by the Library of Congress. It is ...
are frequently used in distributed searching. A benefit to this approach is that the resource-intensive tasks of indexing and storage are left to the respective servers in the federation. A drawback to this approach is that the search mechanism is limited by the different indexing and ranking capabilities of each database; therefore, making it difficult to assemble a combined result consisting of the most relevant found items. Searching over previously harvested metadata involves searching a locally stored
index Index (or its plural form indices) may refer to: Arts, entertainment, and media Fictional entities * Index (''A Certain Magical Index''), a character in the light novel series ''A Certain Magical Index'' * The Index, an item on a Halo megastru ...
of information that has previously been collected from the libraries in the federation. When a search is performed, the search mechanism does not need to make connections with the digital libraries it is searching—it already has a local representation of the information. This approach requires the creation of an indexing and harvesting mechanism which operates regularly, connecting to all the digital libraries and querying the whole collection in order to discover new and updated resources. OAI-PMH is frequently used by digital libraries for allowing metadata to be harvested. A benefit to this approach is that the search mechanism has full control over indexing and ranking algorithms, possibly allowing more consistent results. A drawback is that harvesting and indexing systems are more resource-intensive and therefore expensive.


Digital preservation

Digital preservation aims to ensure that digital media and information systems are still interpretable into the indefinite future. Each necessary component of this must be migrated, preserved or emulated.Cain, Mark. "Managing Technology: Being a Library of Record in a Digital Age", Journal of Academic Librarianship 29:6 (2003). Typically lower levels of systems (
floppy disk A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined ...
s for example) are emulated, bit-streams (the actual files stored in the disks) are preserved and operating systems are emulated as a
virtual machine In computing, a virtual machine (VM) is the virtualization/ emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized h ...
. Only where the meaning and content of digital media and information systems are well understood is migration possible, as is the case for office documents. However, at least one organization, the Wider Net Project, has created an offline digital library, the eGranary, by reproducing materials on a 6 TB
hard drive A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with mag ...
. Instead of a bit-stream environment, the digital library contains a built-in
proxy server In computer networking, a proxy server is a server application that acts as an intermediary between a client requesting a resource and the server providing that resource. Instead of connecting directly to a server that can fulfill a reques ...
and
search engine A search engine is a software system designed to carry out web searches. They search the World Wide Web in a systematic way for particular information specified in a textual web search query. The search results are generally presented in a ...
so the digital materials can be accessed using an Internet browser. Also, the materials are not preserved for the future. The eGranary is intended for use in places or situations where Internet connectivity is very slow, non-existent, unreliable, unsuitable or too expensive. In the past few years, procedures for
digitizing DigitizationTech Target. (2011, April). Definition: digitization. ''WhatIs.com''. Retrieved December 15, 2021, from https://whatis.techtarget.com/definition/digitization is the process of converting information into a digital (i.e. computer- ...
books at high speed and comparatively low cost have improved considerably with the result that it is now possible to digitize millions of books per year. The Google book-scanning project is also working with libraries to offer digitize books pushing forward on the digitize book realm.


Copyright and licensing

Digital libraries are hampered by
copyright A copyright is a type of intellectual property that gives its owner the exclusive right to copy, distribute, adapt, display, and perform a creative work, usually for a limited time. The creative work may be in a literary, artistic, educatio ...
law because, unlike with traditional printed works, the laws of digital copyright are still being formed. The republication of material on the web by libraries may require permission from rights holders, and there is a conflict of interest between libraries and the publishers who may wish to create online versions of their acquired content for commercial purposes. In 2010, it was estimated that twenty-three percent of books in existence were created before 1923 and thus out of copyright. Of those printed after this date, only five percent were still in print as of 2010. Thus, approximately seventy-two percent of books were not available to the public. There is a dilution of responsibility that occurs as a result of the distributed nature of digital resources. Complex intellectual property matters may become involved since digital material is not always owned by a library. The content is, in many cases,
public domain The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because those rights have expired ...
or self-generated content only. Some digital libraries, such as
Project Gutenberg Project Gutenberg (PG) is a volunteer effort to digitize and archive cultural works, as well as to "encourage the creation and distribution of eBooks." It was founded in 1971 by American writer Michael S. Hart and is the oldest digital libr ...
, work to digitize out-of-copyright works and make them freely available to the public. An estimate of the number of distinct books still existent in library catalogues from 2000 BC to 1960, has been made. The
Fair Use Fair use is a doctrine in United States law that permits limited use of copyrighted material without having to first acquire permission from the copyright holder. Fair use is one of the limitations to copyright intended to balance the interests ...
Provisions (17 USC § 107) under the
Copyright Act of 1976 The Copyright Act of 1976 is a United States copyright law and remains the primary basis of copyright law in the United States, as amended by several later enacted copyright provisions. The Act spells out the basic rights of copyright holders, cod ...
provide specific guidelines under which circumstances libraries are allowed to copy digital resources. Four factors that constitute fair use are "Purpose of the use, Nature of the work, Amount or substantiality used and Market impact". Some digital libraries acquire a license to lend their resources. This may involve the restriction of lending out only one copy at a time for each license, and applying a system of
digital rights management Digital rights management (DRM) is the management of legal access to digital content. Various tools or technological protection measures (TPM) such as access control technologies can restrict the use of proprietary hardware and copyrighted work ...
for this purpose (see also above). The
Digital Millennium Copyright Act The Digital Millennium Copyright Act (DMCA) is a 1998 United States copyright law that implements two 1996 treaties of the World Intellectual Property Organization (WIPO). It criminalizes production and dissemination of technology, devices, or ...
of 1998 was an act created in the United States to attempt to deal with the introduction of digital works. This Act incorporates two treaties from the year 1996. It criminalizes the attempt to circumvent measures which limit access to copyrighted materials. It also criminalizes the act of attempting to circumvent access control.United States Copyright Office
"The Digital Millennium Copyright Act of 1998 – U.S. Copyright Office Summary"
1998, 2.
This act provides an exemption for nonprofit libraries and archives which allows up to three copies to be made, one of which may be digital. This may not be made public or distributed on the web, however. Further, it allows libraries and archives to copy a work if its format becomes obsolete. Copyright issues persist. As such, proposals have been put forward suggesting that digital libraries be exempt from copyright law. Although this would be very beneficial to the public, it may have a negative economic effect and authors may be less inclined to create new works. Another issue that complicates matters is the desire of some publishing houses to restrict the use of digit materials such as e-books purchased by libraries. Whereas with printed books, the library owns the book until it can no longer be circulated, publishers want to limit the number of times an e-book can be checked out before the library would need to repurchase that book. " arperCollinsbegan licensing use of each e-book copy for a maximum of 26 loans. This affects only the most popular titles and has no practical effect on others. After the limit is reached, the library can repurchase access rights at a lower cost than the original price." While from a publishing perspective, this sounds like a good balance of library lending and protecting themselves from a feared decrease in book sales, libraries are not set up to monitor their collections as such. They acknowledge the increased demand of digital materials available to patrons and the desire of a digital library to become expanded to include best sellers, but publisher licensing may hinder the process.


Recommendation systems

Many digital libraries offer recommender systems to reduce
information overload Information overload (also known as infobesity, infoxication, information anxiety, and information explosion) is the difficulty in understanding an issue and effectively making decisions when one has too much information (TMI) about that issue, ...
and help their users discovering relevant literature. Some examples of digital libraries offering recommender systems are
IEEE Xplore IEEE Xplore digital library is a research database for discovery and access to journal articles, conference proceedings, technical standards, and related materials on computer science, electrical engineering and electronics, and allied fields. It ...
,
Europeana Europeana is a web portal created by the European Union containing digitised cultural heritage collections of more than 3,000 institutions across Europe. It includes records of over 50 million cultural and scientific artefacts, brought togethe ...
, and GESIS Sowiport. The recommender systems work mostly based on content-based filtering but also other approaches are used such as
collaborative filtering Collaborative filtering (CF) is a technique used by recommender systems.Francesco Ricci and Lior Rokach and Bracha ShapiraIntroduction to Recommender Systems Handbook Recommender Systems Handbook, Springer, 2011, pp. 1-35 Collaborative filtering ...
and citation-based recommendations. Beel et al. report that there are more than 90 different recommendation approaches for digital libraries, presented in more than 200 research articles. Typically, digital libraries develop and maintain their own recommender systems based on existing search and recommendation frameworks such as Apache Lucene or
Apache Mahout Apache Mahout is a project of the Apache Software Foundation to produce free implementations of distributed or otherwise scalable machine learning algorithms focused primarily on linear algebra. In the past, many of the implementations use the ...
. However, there are also some recommendation-as-a-service provider specializing in offering a recommender system for digital libraries
as a service As a service (AAS) is a business model in which something is being presented to a customer In sales, commerce, and economics, a customer (sometimes known as a client, buyer, or purchaser) is the recipient of a good, service, product or an ...
.


Drawbacks of digital libraries

Digital libraries, or at least their digital collections, unfortunately also have brought their own problems and challenges in areas such as: * User authentication for access to collections *
Copyright A copyright is a type of intellectual property that gives its owner the exclusive right to copy, distribute, adapt, display, and perform a creative work, usually for a limited time. The creative work may be in a literary, artistic, educatio ...
* Digital preservation (see above) * Equity of access (see
digital divide The digital divide is the unequal access to digital technology, including smartphones, tablets, laptops, and the internet. The digital divide creates a division and inequality around access to information and resources. In the Information Age i ...
) *
Interface design User interface (UI) design or user interface engineering is the design of user interfaces for machines and software, such as computers, home appliances, mobile devices, and other electronic devices, with the focus on maximizing usability and ...
*
Interoperability Interoperability is a characteristic of a product or system to work with other products or systems. While the term was initially defined for information technology or systems engineering services to allow for information exchange, a broader defi ...
between systems and software * Information organization * Inefficient or non-existent
taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
practices (especially with historical material) *
Training and development Training and development involve improving the effectiveness of organizations and the individuals and teams within them. Training may be viewed as related to immediate changes in organizational effectiveness via organized instruction, while devel ...
* Quality of
metadata Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the descriptive ...
* Exorbitant cost of building/maintaining the terabytes of storage, servers, and redundancies necessary for a functional digital collection. There are many large scale digitisation projects that perpetuate these problems.


Future development

Large scale digitization projects are underway at
Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...
, the Million Book Project, and
Internet Archive The Internet Archive is an American digital library with the stated mission of "universal access to all knowledge". It provides free public access to collections of digitized materials, including websites, software applications/games, music, ...
. With continued improvements in book handling and presentation technologies such as
optical character recognition Optical character recognition or optical character reader (OCR) is the electronic or mechanical conversion of images of typed, handwritten or printed text into machine-encoded text, whether from a scanned document, a photo of a document, a sc ...
and development of alternative depositories and business models, digital libraries are rapidly growing in popularity. Just as libraries have ventured into audio and video collections, so have digital libraries such as the Internet Archive.
Google Books Google Books (previously known as Google Book Search, Google Print, and by its code-name Project Ocean) is a service from Google Inc. that searches the full text of books and magazines that Google has scanned, converted to text using optical ...
project recently received a court victory on proceeding with their book-scanning project that was halted by the Authors' guild. This helped open the road for libraries to work with Google to better reach patrons who are accustomed to computerized information. According to Larry Lannom, Director of Information Management Technology at the nonprofit Corporation for National Research Initiatives (CNRI), "all the problems associated with digital libraries are wrapped up in archiving". He goes on to state, "If in 100 years people can still read your article, we'll have solved the problem." Daniel Akst, author of The Webster Chronicle, proposes that "the future of libraries—and of information—is digital". Peter Lyman and Hal Variant, information scientists at the
University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant un ...
, estimate that "the world's total yearly production of print, film, optical, and magnetic content would require roughly 1.5 billion gigabytes of storage". Therefore, they believe that "soon it will be technologically possible for an average person to access virtually all recorded information". Digital archives are an evolving medium and they develop under various circumstances. Alongside large scale repositories, other digital archiving projects have also evolved in response to needs in research and research communication on various institutional levels. For example, during the
COVID-19 pandemic The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identi ...
,
libraries A library is a collection of Document, materials, books or media that are accessible for use and not just for display purposes. A library provides physical (hard copies) or electronic media, digital access (soft copies) materials, and may be a ...
and higher education institutions have launched digital archiving projects to document life during the pandemic, thus creating a digital, cultural record of
collective memories A collective is a group of entities that share or are motivated by at least one common issue or interest, or work together to achieve a common objective. Collectives can differ from cooperatives in that they are not necessarily focused upon an ...
from the period. Researchers have also utilized digital archiving to create specialized research databases. These databases compile digital records for use on international and interdisciplinary levels. COVID CORPUS, launched in October 2020, is an example of such a database, built in response to scientific communication needs in light of the pandemic. Beyond academia, digital collections have also recently been developed to appeal to a more general audience, as is the case with the Selected General Audience Content of the Internet-First University Press developed by Cornell University. This general-audience database contains specialized research information but is digitally organized for accessibility. The establishment of these archives has facilitated specialized forms of digital recordkeeping to fulfill various niches in online, research-based communication.


See also

*
Anna's Archive Anna's Archive is a free non-profit online shadow library metasearch engine providing access to a variety of book resources (also via IPFS), created by a team of anonymous archivists (referred to as Anna and/or the Pirate Library Mirror (PiL ...
*
Bibliographic database A bibliographic database is a database of bibliographic records, an organized digital collection of references to published literature, including journal and newspaper articles, conference proceedings, reports, government and legal publications, ...
* Content repository * Digital Library Federation * Digital Collections Selection Criteria *
Digitization DigitizationTech Target. (2011, April). Definition: digitization. ''WhatIs.com''. Retrieved December 15, 2021, from https://whatis.techtarget.com/definition/digitization is the process of converting information into a digital (i.e. computer-r ...
* '' D-Lib'', magazine about digital libraries *
Full-text database A full-text database or a complete-text database is a database that contains the complete text of books, dissertations, journals, magazines, newspapers or other kinds of textual documents. They differ from bibliographic databases (which con ...
*
List of digital library projects This is a list of digital library projects. See also * Bibliographic database * List of academic databases and search engines * List of online databases * List of online encyclopedias * List of open-access journals * List of search engines ...
*
Mobile library A bookmobile or mobile library is a vehicle designed for use as a library. They have been known by many names throughout history, including traveling library, library wagon, book wagon, book truck, library-on-wheels, and book auto service. Bookm ...
*
Shadow library Shadow libraries are online databases of readily available content that is normally obscured or otherwise not readily accessible. Such content may be inaccessible for a number of reasons, including the use of paywalls, copyright controls, or othe ...
*
Traveling library A traveling library is a collection of books lent for stated periods by a central library to a branch library, club, or other organization or, in some instances, to an individual. The chief characteristics from which it derives its name are its temp ...
* Web archive


References


Further reading

* * Pomerantz, Jeffrey, and Gary Marchionini. 2007. "The Digital Library as Place". ''Journal of Documentation'' 63(4): 505–33.


External links

{{Authority control Library science Types of library