In computing, a Digital Object Identifier or DOI is a persistent
identifier or handle used to uniquely identify objects, standardized
International Organization for Standardization
International Organization for Standardization (ISO). An
implementation of the Handle System, DOIs are in wide use mainly
to identify academic, professional, and government information, such
as journal articles, research reports and data sets, and official
publications though they also have been used to identify other types
of information resources, such as commercial videos.
A DOI aims to be "resolvable", usually to some form of access to the
information object to which the DOI refers. This is achieved by
binding the DOI to metadata about the object, such as a URL,
indicating where the object can be found. Thus, by being actionable
and interoperable, a DOI differs from identifiers such as ISBNs and
ISRCs which aim only to uniquely identify their referents. The DOI
system uses the indecs Content Model for representing metadata.
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 shall provide a more stable
linking than simply using its URL. Every time a
URL changes, the
publisher has to update the metadata for the DOI to link to the new
URL. It is the publisher's responsibility to update the DOI
database. By failing 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.
1 Nomenclature and syntax
3 Features and benefits
4 Comparison with other identifier schemes
6 IDF organizational structure
8 See also
11 External links
Nomenclature and syntax
A DOI is a type of
Handle System handle, which takes the form of a
character string divided into two parts, a prefix and a suffix,
separated by a slash.
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
Unicode characters are allowed in
these strings, which are interpreted in a case-insensitive manner. The
prefix usually takes the form 10.NNNN, where NNNN is a series of at
least 4 numbers 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 10.NNNN.N.
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
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
The official DOI Handbook explicitly states that DOIs should display
on screens and in print in the format doi:10.1000/182.
Contrary to the DOI Handbook, CrossRef, a major DOI registration
agency, recommends displaying a
URL (for example,
https://doi.org/10.1000/182) instead of the officially specified
format (for example, doi:10.1000/182) This
URL is persistent
(there is a contract that ensures persistence in the DOI.ORG domain),
so it is a P
URL — providing the location of an
HTTP proxy server
which will redirect web accesses to the correct online location of the
CrossRef recommendation is primarily based on the assumption that
the DOI is being displayed without being hyper-linked to its
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.
Major applications of the DOI system currently include:
scholarly materials (journal articles, books, ebooks,etc.) through
CrossRef, a consortium of around 3,000 publishers; Airiti, a leading
provider of electronic academic journals in Chinese and Taiwanese; 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
European Union official publications through the EU publications
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 commercial video content through the
Entertainment ID Registry, commonly known as EIDR.
In the Organisation for Economic Co-operation and Development's
publication service OECD iLibrary, each table or graph in an OECD
publication is shown with a DOI name that leads to an Excel file of
data underlying the tables and graphs. Further development of such
services is planned.
Other registries include
Crossref and the multilingual European DOI
Registration Agency. Since 2015 RFCs can be referenced as
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. 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.
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
URL 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
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
Uniform Resource Locator (URL), in that it identifies an
object itself as a first-class entity, rather than the specific place
where the object is located at a certain time. It implements the
Uniform Resource Identifier (Uniform Resource Name) concept and adds
to it a data model and social infrastructure.
A DOI name also differs from standard identifier registries such as
the ISBN, ISRC, etc. The purpose of an identifier registry is to
manage a given collection of identifiers, whereas the primary purpose
of the DOI system is to make a collection of identifiers actionable
and interoperable, where that collection can include identifiers from
many other controlled collections.
The DOI system offers persistent, semantically-interoperable
resolution to related current data and is best suited to material that
will be used in services outside the direct control of the issuing
assigner (e.g., public citation or managing content of value). It uses
a managed registry (providing social and technical infrastructure). It
does not assume any specific business model for the provision of
identifiers or services and enables other existing services to link to
it in defined ways. Several approaches for making identifiers
persistent have been proposed. The comparison of persistent identifier
approaches is difficult because they are not all doing the same thing.
Imprecisely referring to a set of schemes as "identifiers" doesn't
mean that they can be compared easily. Other "identifier systems" may
be enabling technologies with low barriers to entry, providing an easy
to use labeling mechanism that allows anyone to set up a new instance
(examples include Persistent
Uniform Resource Locator (PURL), URLs,
Globally Unique Identifiers (GUIDs), etc.), but may lack some of the
functionality of a registry-controlled scheme and will usually lack
accompanying metadata in a controlled scheme. The DOI system does not
have this approach and should not be compared directly to such
identifier schemes. Various applications using such enabling
technologies with added features have been devised that meet some of
the features offered by the DOI system for specific sectors (e.g.,
A DOI name does not depend on the object's location and, in this way,
is similar to a
Uniform Resource Name (URN) or P
URL but differs from
an ordinary URL. URLs are often used as substitute identifiers for
documents on the Internet (better characterised as Uniform Resource
Identifiers) 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
To resolve a DOI name, it may be input to a DOI resolver, such as
Another approach, which avoids typing or cutting-and-pasting into a
resolver is to include the DOI in a document as a
URL which uses the
resolver as an HTTP proxy, such as http://doi.org/ (preferred) or
http://dx.doi.org/, both of which support HTTPS. For example, the DOI
10.1000/182 can 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. Indeed, as previously mentioned, this
CrossRef recommends that DOIs always be represented (preferring
HTTPS over HTTP), so that if they are cut-and-pasted into other
documents, emails, etc., they will be actionable.
Other DOI resolvers and HTTP Proxies include http://hdl.handle.net,
http://doi.medra.org, https://doi.pangaea.de/. At the beginning of the
year 2016, a new class of alternative DOI resolvers was started by
http://doai.io. This service is unusual in that it tries to find a
non-paywalled version of a title and redirects you to that instead of
the publisher's version. Since then, other open-access
favoring DOI resolvers have been created, notably https://oadoi.org/
in October 2016. While traditional DOI resolvers solely rely on
the Handle System, alternative DOI resolvers first consult open access
resources such as BASE (Bielefeld Academic Search Engine).
An alternative to HTTP proxies is to use one of a number of add-ons
and plug-ins for browsers, thereby avoiding the conversion of the DOIs
to URLs, which depend on domain names and may be subject to
change, while still allowing the DOI to be treated as a normal
hyperlink. For example. the CNRI Handle Extension for
Firefox[permanent dead link], enables the browser to access Handle
System handles or DOIs like hdl:4263537/4000 or doi:10.1000/1 directly
Firefox browser, using the native
Handle System protocol. This
plug-in can also replace references to web-to-handle proxy servers
with native resolution. A disadvantage of this approach for publishers
is that, at least at present, most users will be encountering the DOIs
in a browser, mail reader, or other software which does not have one
of these plug-ins installed.
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 10 prefix.
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 not-for-profit cost recovery
The DOI system is an international standard developed by the
International Organization for Standardization
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
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 info URI scheme specified by IETF
RFC 4452. info:doi/ is the infoURI Namespace of Digital Object
The DOI syntax is a N
ISO standard, first standardised in 2000,
ISO Z39.84-2005 Syntax for the Digital Object Identifier.
The maintainers of the DOI system have deliberately not registered a
DOI namespace for URNs, stating that:
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:10.1000/1 rather
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
— International DOI Foundation, Factsheet: DOI System and Internet
Publisher Item Identifier (PII)
Universally Unique Identifier (UUID)
^ Other registries are identified by other strings at the start of the
prefix. Handle names that begin with "100." are also in use, as for
example in the following citation: Hammond, Joseph L., Jr.; Brown,
James E.; Liu, Shyan-Shiang S. (May 1975). "Development of a
Transmission Error Model and an Error Control Model l". Technical
Report RADC-TR-75-138. Rome Air Development Center.
^ a b "
ISO 26324:2012(en), Information and documentation — Digital
object identifier system". ISO. Retrieved 2016-04-20.
^ "The Handle System".
^ Witten, Ian H.; David Bainbridge & David M. Nichols (2010). How
to Build a Digital Library (2nd ed.). Amsterdam; Boston: Morgan
Kaufmann. pp. 352–253. ISBN 978-0-12-374857-7.
^ Langston, Marc; Tyler, James (2004). "Linking to journal articles in
an online teaching environment: The persistent link, DOI, and
OpenURL". The Internet and Higher Education. 7 (1): 51–58.
^ "How the 'Digital Object Identifier' works". BusinessWeek.
BusinessWeek. 23 July 2001. 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
^ a b Davidson, Lloyd A.; Douglas, Kimberly (December 1998). "Digital
Object Identifiers: Promise and problems for scholarly publishing".
Journal of Electronic Publishing. 4 (2).
^ "Welcome to the DOI System". Doi.org. 28 June 2010. Retrieved 7
^ "DOI® News, April 2011: 1. DOI System exceeds 50 million assigned
identifiers". Doi.org. 20 April 2011. Retrieved 3 July 2011.
^ "doi info & guidelines". CrossRef.org. Publishers International
Linking Association, Inc. 2013. 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). [permanent
^ "Factsheet—Key Facts on Digital Object Identifier System".
doi.org. International DOI Foundation. June 6, 2016. Retrieved 10 June
2016. Over 18,000 DOI name prefixes within the DOI System
^ "DOI Handbook—2 Numbering". doi.org. International DOI Foundation.
February 1, 2016. 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: 2. What can be
identified by a DOI name?". International DOI Foundation. 17 February
2010 [update of earlier version]. Retrieved 23 April 2010.
^ "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".
Crossref DOI display guidelines are on the way".
^ Powell, Andy (June 1998). "Resolving DOI Based URNs Using Squid: An
Experimental System at UKOLN". D-Lib Magazine.
^ Green, T. (2009). "We Need Publishing Standards for Datasets and
Data Tables". Research Information. doi:10.1787/603233448430.
^ "multilingual European DOI Registration Agency". mEDRA.org.
John R. Levine
John R. Levine (2015). "DOIs for RFCs". RFC 7669. IAB.
^ Timmer, John (6 March 2010). "DOIs and their discontents". Ars
Technica. Retrieved 5 March 2013.
^ DeRisi, Susanne; Kennison, Rebecca; Twyman, Nick (2003). "Editorial:
The what and whys of DOIs". PLoS Biology. 1 (2): e57.
doi:10.1371/journal.pbio.0000057. PMC 261894 .
^ Franklin, Jack (2003). "
Open access to scientific and technical
information: the state of the art". In Grüttemeier, Herbert; Mahon,
Open access to scientific and technical information: state of
the art and future trends. IOS Press. p. 74.
^ "DOI System and Internet Identifier Specifications". Doi.org. 18 May
2010. Retrieved 7 August 2010.
^ "DOI System and standard identifier registries". Doi.org. Retrieved
7 August 2010.
^ International DOI Foundation (2014-08-07). "Resolution". DOI
Handbook. Retrieved 19 March 2015.
^ a b "DOAI". CAPSH (Committee for the Accessibility of Publications
in Sciences and Humanities). Retrieved 6 August 2016.
^ Schonfeld, Roger C. (2016-03-03). "Co-opting 'Official' Channels
through Infrastructures for Openness". The Scholarly Kitchen.
^ a b Piwowar, Heather (2016-10-25). "Introducing oaDOI: resolve a DOI
straight to OA". Retrieved 2017-03-17.
^ "DOI System Tools".
^ "Chapter 7: The International DOI Foundation". DOI Handbook.
Doi.org. Retrieved 8 July 2015.
^ "DONA Foundation Multi-Primary Administrators".
Digital object identifier
Digital object identifier (DOI) becomes an
ISO standard". iso.org.
10 May 2012. Retrieved 10 May 2012.
^ "about_the_doi.html DOI Standards and Specifications". Doi.org. 28
June 2010. Retrieved 7 August 2010.
^ "Overviews & Standards – Standards and Specifications: 1. ISO
TC46/SC9 Standards". Doi.org. 18 November 2010. Retrieved 3 July
^ "About "info" URIs – Frequently Asked Questions". Info-uri.info.
Retrieved 7 August 2010.
ISO Z39.84-2000 Syntax for the Digital Object Identifier".
Techstreet.com. Retrieved 7 August 2010.
^ International DOI Foundation (2012).
Wikidata has the property: DOI (P356) (see talk; uses)
Short DOI – DOI Foundation service for converting long DOIs to
Factsheet: DOI System and Internet Identifier Specifications
CrossRef DOI lookup
International numbering standards
International Standard Book Number
International Standard Book Number (ISBN)
International Standard Serial Number
International Standard Serial Number (ISSN)
International Standard Recording Code (ISRC)
International Securities Identification Number (ISIN)
ISO/IEC 7812: Issuer identification number (IIN)
International Standard Music Number
International Standard Music Number (ISMN)
International Bank Account Number
International Bank Account Number (IBAN)
ISO 15511: International Standard Identifier for Libraries... (ISIL)
International Standard Audiovisual Number
International Standard Audiovisual Number (ISAN)
International Standard Musical Work Code (ISWC)
International Standard Link Identifier (ISLI)
Legal Entity Identifier (LEI)
International Standard Text Code (ISTC)
ISO 26324: Digital Object Identifier System (DOI)
International Standard Name Identifier (ISNI)
Virtual International Authority
ISO standards by standard number
ISO standards /
ISO romanizations / IEC standards