|Full name||Digital object identifier|
|Organisation||International DOI Foundation|
A digital object identifier (DOI) is a persistent identifier or handle used to uniquely identify various objects, standardized by the International Organization for Standardization (ISO). DOIs are an implementation of the Handle System; they also fit within the URI system (Uniform Resource Identifier). They are widely used to identify academic, professional, and government information, such as journal articles, research reports, data sets, and official publications. DOIs have also been used to identify other types of information resources, such as commercial videos.
A DOI aims to resolve to its target, the information object to which the DOI refers. This is achieved by binding the DOI to
The DOI for a document remains fixed over the lifetime of the document, whereas its location and other metadata may change. Referring to an online document by its DOI should provide a more stable link than directly using its URL. But if its URL changes, the publisher must update the metadata for the DOI to maintain the link to the URL. It is the publisher's responsibility to update the DOI database. If they fail to do so, the DOI resolves to a dead link, leaving the DOI useless.
The developer and administrator of the DOI system is the International DOI Foundation (IDF), which introduced it in 2000. Organizations that meet the contractual obligations of the DOI system and are willing to pay to become a member of the system can assign DOIs. The DOI system is implemented through a federation of registration agencies coordinated by the IDF. By late April 2011 more than 50 million DOI names had been assigned by some 4,000 organizations, and by April 2013 this number had grown to 85 million DOI names assigned through 9,500 organizations.
Nomenclature and syntax
A DOI is a type of Handle System handle, which takes the form of a
The prefix identifies the registrant of the identifier and the suffix is chosen by the registrant and identifies the specific object associated with that DOI. Most legal
NNNNis a number greater than or equal to
1000, whose limit depends only on the total number of registrants. The prefix may be further subdivided with periods, like
For example, in the DOI name
10.1000/182, the prefix is
10.1000 and the suffix is
182. The "10" part of the prefix distinguishes the handle as part of the DOI namespace, as opposed to some other Handle System namespace,[A] and the characters
1000 in the prefix identify the registrant; in this case the registrant is the International DOI Foundation itself.
182 is the suffix, or item ID, identifying a single object (in this case, the latest version of the DOI Handbook).
DOI names can identify creative works (such as texts, images, audio or video items, and software) in both electronic and physical forms, performances, and abstract works such as licenses, parties to a transaction, etc.
The names can refer to objects at varying levels of detail: thus DOI names can identify a journal, an individual issue of a journal, an individual article in the journal, or a single table in that article. The choice of level of detail is left to the assigner, but in the DOI system it must be declared as part of the metadata that is associated with a DOI name, using a data dictionary based on the indecs Content Model.
The official DOI Handbook explicitly states that DOIs should display on screens and in print in the format
Contrary to the DOI Handbook,
The CrossRef recommendation is primarily based on the assumption that the DOI is being displayed without being hyperlinked to its appropriate URL – the argument being that without the hyperlink it is not as easy to copy-and-paste the full URL to actually bring up the page for the DOI, thus the entire URL should be displayed, allowing people viewing the page containing the DOI to copy-and-paste the URL, by hand, into a new window/tab in their browser in order to go to the appropriate page for the document the DOI represents.
Since DOI is a namespace within the Handle System, it is semantically correct to represent it as the URI
Major content of the DOI system currently includes:
- Scholarly materials (journal articles, books, ebooks, etc.) through Crossref, a consortium of around 3,000 publishers; Airiti, a leading provider of Chinese and Taiwanese electronic academic journals; and the Japan Link Center (JaLC)  an organization providing link management and DOI assignment for electronic academic journals in Japanese.
- Research datasets through Datacite, a consortium of leading research libraries, technical information providers, and scientific data centers;
- EU publications office;
- The Chinese National Knowledge Infrastructure project at Tsinghua University and the Institute of Scientific and Technical Information of China (ISTIC), two initiatives sponsored by the Chinese government.
- Permanent global identifiers for both commercial and non-commercial audio/visual content titles, edits, and manifestations through the Entertainment ID Registry, commonly known as EIDR.
Features and benefits
The IDF designed the DOI system to provide a form of persistent identification, in which each DOI name permanently and unambiguously identifies the object to which it is associated (although when the publisher of a journal changes, sometimes all the DOIs will be changed, with the old DOIs no longer working). It also associates metadata with objects, allowing it to provide users with relevant pieces of information about the objects and their relationships. Included as part of this metadata are network actions that allow DOI names to be resolved to web locations where the objects they describe can be found. To achieve its goals, the DOI system combines the Handle System and the indecs Content Model with a social infrastructure.
The Handle System ensures that the DOI name for an object is not based on any changeable attributes of the object such as its physical location or ownership, that the attributes of the object are encoded in its metadata rather than in its DOI name, and that no two objects are assigned the same DOI name. Because DOI names are short character strings, they are human-readable, may be copied and pasted as text, and fit into the URI specification. The DOI name-resolution mechanism acts behind the scenes, so that users communicate with it in the same way as with any other web service; it is built on open architectures, incorporates trust mechanisms, and is engineered to operate reliably and flexibly so that it can be adapted to changing demands and new applications of the DOI system. DOI name-resolution may be used with OpenURL to select the most appropriate among multiple locations for a given object, according to the location of the user making the request. However, despite this ability, the DOI system has drawn criticism from librarians for directing users to non-free copies of documents, that would have been available for no additional fee from alternative locations.
The indecs Content Model as used within the DOI system associates metadata with objects. A small kernel of common metadata is shared by all DOI names and can be optionally extended with other relevant data, which may be public or restricted. Registrants may update the metadata for their DOI names at any time, such as when publication information changes or when an object moves to a different URL.
The International DOI Foundation (IDF) oversees the integration of these technologies and operation of the system through a technical and social infrastructure. The social infrastructure of a federation of independent registration agencies offering DOI services was modelled on existing successful federated deployments of identifiers such as GS1 and ISBN.
Comparison with other identifier schemes
A DOI name differs from commonly used Internet pointers to material, such as the
A DOI name also differs from standard identifier registries such as the
The DOI system offers persistent,
A DOI name does not depend on the object's location and, in this way, is similar to a Uniform Resource Name (URN) or PURL but differs from an ordinary URL. URLs are often used as substitute identifiers for documents on the Internet although the same document at two different locations has two URLs. By contrast, persistent identifiers such as DOI names identify objects as first class entities: two instances of the same object would have the same DOI name.
DOI name resolution is provided through the Handle System, developed by Corporation for National Research Initiatives, and is freely available to any user encountering a DOI name. Resolution redirects the user from a DOI name to one or more pieces of typed data: URLs representing instances of the object, services such as e-mail, or one or more items of metadata. To the Handle System, a DOI name is a handle, and so has a set of values assigned to it and may be thought of as a record that consists of a group of fields. Each handle value must have a data type specified in its
<type> field, which defines the syntax and semantics of its data. While a DOI persistently and uniquely identifies the object to which it is assigned, DOI resolution may not be persistent, due to technical and administrative issues.
To resolve a DOI name, it may be input to a DOI resolver, such as doi.org.
Another approach, which avoids typing or
http://dx.doi.org/, both of which support HTTPS. For example, the DOI
10.1000/182can be included in a reference or hyperlink as
https://doi.org/10.1000/182. This approach allows users to click on the DOI as a normal hyperlink
Other DOI resolvers and HTTP Proxies include the
An alternative to HTTP proxies is to use one of a number of add-ons and plug-ins for
IDF organizational structure
The International DOI Foundation (IDF), a non-profit organisation created in 1998, is the governance body of the DOI system. It safeguards all intellectual property rights relating to the DOI system, manages common operational features, and supports the development and promotion of the DOI system. The IDF ensures that any improvements made to the DOI system (including creation, maintenance, registration, resolution and policymaking of DOI names) are available to any DOI registrant. It also prevents third parties from imposing additional licensing requirements beyond those of the IDF on users of the DOI system.
The IDF is controlled by a Board elected by the members of the Foundation, with an appointed Managing Agent who is responsible for co-ordinating and planning its activities. Membership is open to all organizations with an interest in electronic publishing and related enabling technologies. The IDF holds annual open meetings on the topics of DOI and related issues.
Registration agencies, appointed by the IDF, provide services to DOI registrants: they allocate DOI prefixes, register DOI names, and provide the necessary infrastructure to allow registrants to declare and maintain metadata and state data. Registration agencies are also expected to actively promote the widespread adoption of the DOI system, to cooperate with the IDF in the development of the DOI system as a whole, and to provide services on behalf of their specific user community. A list of current RAs is maintained by the International DOI Foundation. The IDF is recognized as one of the federated registrars for the Handle System by the DONA Foundation (of which the IDF is a board member), and is responsible for assigning Handle System prefixes under the top-level
Registration agencies generally charge a fee to assign a new DOI name; parts of these fees are used to support the IDF. The DOI system overall, through the IDF, operates on a
The DOI system is an international standard developed by the International Organization for Standardization in its technical committee on identification and description, TC46/SC9. The Draft International Standard ISO/DIS 26324, Information and documentation – Digital Object Identifier System met the ISO requirements for approval. The relevant ISO Working Group later submitted an edited version to ISO for distribution as an FDIS (Final Draft International Standard) ballot, which was approved by 100% of those voting in a ballot closing on 15 November 2010. The final standard was published on 23 April 2012.
DOI is a registered URI under the
The DOI syntax is a
The maintainers of the DOI system have deliberately not registered a DOI namespace for
URN architecture assumes a DNS-based Resolution Discovery Service (RDS) to find the service appropriate to the given URN scheme. However no such widely deployed RDS schemes currently exist.... DOI is not registered as a URN namespace, despite fulfilling all the functional requirements, since URN registration appears to offer no advantage to the DOI System. It requires an additional layer of administration for defining DOI as a URN namespace (the string
urn:doi:10.1000/1rather than the simpler
doi:10.1000/1) and an additional step of unnecessary redirection to access the resolution service, already achieved through either http proxy or native resolution. If RDS mechanisms supporting URN specifications become widely available, DOI will be registered as a URN.— International DOI Foundation, Factsheet: DOI System and Internet Identifier Specifications
- Other registries are identified by other strings at the start of the prefix.
- "The Handle System". Handle.Net Registry. Archived from the original on 7 January 2023.
- "Factsheets". DOI. Archived from the original on 25 December 2022.
- "How the "Digital Object Identifier" Works". BusinessWeek. 23 July 2001. Archived from the original on 2 October 2010. Retrieved 20 April 2010.
Assuming the publishers do their job of maintaining the databases, these centralized references, unlike current web links, should never become outdated or broken
- Paskin, Norman (2010), "Digital Object Identifier (DOI) System", Encyclopedia of Library and Information Sciences (3rd ed.), Taylor and Francis, pp. 1586–1592
- "Welcome to the DOI System". Doi.org. 28 June 2010. Archived from the original on 13 August 2010. Retrieved 7 August 2010.
- "DOI News, April 2011: 1. DOI System exceeds 50 million assigned identifiers". Doi.org. 20 April 2011. Archived from the original on 27 July 2011. Retrieved 3 July 2011.
- "doi info & guidelines". CrossRef.org. Publishers International Linking Association, Inc. 2013. Archived from the original on 21 October 2002. Retrieved 10 June 2016.
All DOI prefixes begin with "10" to distinguish the DOI from other implementations of the Handle System followed by a four-digit number or string (the prefix can be longer if necessary).
- "Factsheet—Key Facts on Digital Object Identifier System". doi.org. International DOI Foundation. 6 June 2016. Archived from the original on 5 June 2016. Retrieved 10 June 2016.
Over 18,000 DOI name prefixes within the DOI System
- "DOI Handbook—2 Numbering". doi.org. International DOI Foundation. 1 February 2016. Archived from the original on 30 June 2014. Retrieved 10 June 2016.
The registrant code may be further divided into sub-elements for administrative convenience if desired. Each sub-element of the registrant code shall be preceded by a full stop.
- "Frequently asked questions about the DOI system: 6. What can a DOI name be assigned to?". DOI Foundation. 3 July 2018. Archived from the original on 16 February 2023. Retrieved 19 July 2018.
- "DOI Handbook – Numbering". doi.org. 13 February 2014. Section 2.6.1 Screen and print presentation. Archived from the original on 30 June 2014. Retrieved 30 June 2014.
- "DOI Display Guidelines". Archived from the original on 24 November 2016. Retrieved 19 October 2016.
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- "Japan Link Center(JaLC)". japanlinkcenter.org. Archived from the original on 29 September 2020. Retrieved 6 August 2022.
- "multilingual European DOI Registration Agency". mEDRA.org. 2003. Archived from the original on 1 February 2018. Retrieved 2 February 2018.
- Timmer, John (6 March 2010). "DOIs and their discontents". Ars Technica. Archived from the original on 8 March 2013. Retrieved 5 March 2013.
- "DOI System and Internet Identifier Specifications". Doi.org. 18 May 2010. Archived from the original on 26 June 2010. Retrieved 7 August 2010.
- "DOI System and standard identifier registries". Doi.org. Archived from the original on 26 June 2010. Retrieved 7 August 2010.
- International DOI Foundation (7 August 2014). "Resolution". DOI Handbook. Archived from the original on 31 March 2015. Retrieved 19 March 2015.
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- Schonfeld, Roger C. (3 March 2016). "Co-opting 'Official' Channels through Infrastructures for Openness". The Scholarly Kitchen. Archived from the original on 19 October 2016. Retrieved 17 October 2016.
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- "Digital object identifier (DOI) becomes an ISO standard". International Organization for Standardization. 10 May 2012. Archived from the original on 2 August 2012. Retrieved 10 May 2012.
- "Standards and Specifications". Overviews & Standards. Doi.org. 28 June 2010. Archived from the original on 26 June 2010. Retrieved 7 August 2010.
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- "ANSI/NISO Z39.84-2005 Syntax for the Digital Object Identifier" (PDF). National Information Standards Organization. Archived (PDF) from the original on 25 June 2021. Retrieved 25 June 2021.
- Official website
- Short DOI – DOI Foundation service for converting long DOIs to shorter equivalents
- Factsheet: DOI System and Internet Identifier Specifications
- CrossRef DOI lookup