# Linked data

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Structured data and method for its publication

Not to be confused with [Linked data structure](/source/Linked_data_structure).

Wikidata in the Linked Open Data Cloud, as at August 2020. Databases indicated as circles (with wikidata indicated as ‘WD’), with grey lines linking databases in the network if their data is aligned. Generated from [https://lod-cloud.net/datasets](https://lod-cloud.net/datasets) .

DBpedia as the most interlinked LOD dataset and crystallization point of the Linked Open Data Cloud since 2008. Image from 2021, generated from https://lod-cloud.net.

In computing, **linked data** is structured data which is associated with ("linked" to) other data. Interlinking makes the data more useful through semantic queries. Tim Berners-Lee, director of the World Wide Web Consortium (W3C), coined the term in a 2006 design note about the Semantic Web project. Part of the vision of linked data is for the Internet to become a global database.

Linked data builds upon standard Web technologies such as HTTP, RDF and URIs, but rather than using them to serve web pages and hyperlinks only for human readers, it extends them to share information in a way that can be read automatically by computers (machine readable). Linked data may also be open data, in which case it is usually described as *Linked Open Data*.

## Principles

In his 2006 "Linked Data" note, [Tim Berners-Lee](/source/Tim_Berners-Lee) outlined four principles of linked data, paraphrased along the following lines:[1]

1. [Uniform Resource Identifiers](/source/Uniform_Resource_Identifier) (URIs) should be used to name and identify individual things.

1. [HTTP](/source/Hypertext_Transfer_Protocol) URIs should be used to allow these things to be looked up, interpreted, and subsequently "dereferenced".

1. Useful information about what a name identifies should be provided through open standards such as [RDF](/source/Resource_Description_Framework), [SPARQL](/source/SPARQL), etc.

1. When publishing data on the Web, other things should be referred to using their HTTP URI-based names.

Tim Berners-Lee later restated these principles at a 2009 [TED conference](/source/TED_(conference)), again paraphrased along the following lines:[2]

1. All conceptual things should have a name starting with [HTTP](/source/HTTP).

1. Looking up an HTTP name should return useful data about the thing in question in a standard format.

1. Anything else that that same thing has a relationship with through its data should also be given a name beginning with HTTP.

## Components

Thus, we can identify the following components as essential to a global Linked Data system as envisioned, and to any actual Linked Data subset within it:

- [URIs](/source/Uniform_resource_identifier)

- [HTTP](/source/HTTP)

- [Structured data](/source/Structured_data) using [controlled vocabulary](/source/Controlled_vocabulary) terms and dataset definitions expressed in [Resource Description Framework](/source/Resource_Description_Framework) [serialization](/source/Serialization) formats such as [RDFa](/source/RDFa), [RDF/XML](/source/RDF%2FXML), [N3](/source/Notation_3), [Turtle](/source/Turtle_(syntax)), or [JSON-LD](/source/JSON-LD)

- [Linked Data Platform](/source/Linked_Data_Platform)

- [CSV](/source/CSV_(file_format))-W[3]

## Linked open data

**Linked open data** are linked data that are [open data](/source/Open_data).[4][5][6] Tim Berners-Lee gives the clearest definition of linked open data as differentiated from linked data.

Linked Open Data (LOD) is Linked Data which is released under an open license, which does not impede its reuse for free.

— Tim Berners-Lee, Linked Data[1][7]

Large linked open data sets include [DBpedia](/source/DBpedia), [Wikibase](/source/Wikibase), [Wikidata](/source/Wikidata) and [Open ICEcat](https://en.wikipedia.org/w/index.php?title=Open_ICEcat&action=edit&redlink=1) [[uk](https://uk.wikipedia.org/wiki/Open_ICEcat); [nl](https://nl.wikipedia.org/wiki/Open_ICEcat)].

### 5-star linked open data

Deployment scheme for Linked Open Data[8]

In 2010, [Tim Berners-Lee](/source/Tim_Berners-Lee) suggested a 5-star scheme for grading the quality of open data on the web, for which the highest ranking is Linked Open Data:[9]

- 1 star: data is openly available in some format.

- 2 stars: data is available in a structured format, such as [Microsoft Excel file format](/source/Microsoft_Excel_file_format) (.xls).

- 3 stars: data is available in a non-proprietary structured format, such as [Comma-separated values](/source/Comma-separated_values) (.csv).

- 4 stars: data follows [W3C](/source/World_Wide_Web_Consortium) standards, like using [RDF](/source/Resource_Description_Framework) and employing [URIs](/source/Uniform_Resource_Identifier).

- 5 stars: all of the others, plus links to other Linked Open Data sources.

### History

The term "linked open data" has been in use since at least February 2007, when the "Linking Open Data" mailing list[10] was created.[11] The mailing list was initially hosted by the [SIMILE](/source/SIMILE) project[12] at the [Massachusetts Institute of Technology](/source/Massachusetts_Institute_of_Technology).

### Linking Open Data community project

The above diagram shows which Linking Open Data datasets are connected, as of August 2014.  This was produced by the Linked Open Data Cloud project, which was started in 2007.  Some sets may include copyrighted data which is freely available.[13]

The same diagram as above, but for February 2017, showing the growth in just two and a half years

The LOD cloud in December 2024

The goal of the W3C Semantic Web Education and Outreach group's Linking Open Data community project is to extend the Web with a [data commons](/source/Knowledge_commons) by publishing various [open](/source/Open_knowledge) [datasets](/source/Dataset) as RDF on the Web and by setting [RDF](/source/Resource_Description_Framework) links between data items from different data sources. In October 2007, datasets consisted of over two billion RDF [triples](/source/Semantic_triple), which were interlinked by over two million RDF links.[14][15] By September 2011 this had grown to 31 billion RDF triples, interlinked by around 504 million RDF links. A detailed statistical breakdown was published in 2014.[16]

### European Union projects

There are a number of [European Union](/source/European_Union) projects involving linked data. These include the linked open data around the clock (LATC) project,[17] the AKN4EU project for machine-readable legislative data,[18] the PlanetData project,[19] the DaPaaS (Data-and-Platform-as-a-Service) project,[20] and the Linked Open Data 2 (LOD2) project.[21][22][23] Data linking is one of the main goals of the [EU Open Data Portal](/source/EU_Open_Data_Portal), which makes available thousands of datasets for anyone to reuse and link.

### Ontologies

[Ontologies](/source/Ontology_(information_science)) are formal descriptions of data structures. Some of the better known ontologies are:

- [FOAF](/source/FOAF_(ontology)) – an ontology describing persons, their properties and relationships

- [UMBEL](/source/UMBEL) – a lightweight reference structure of 20,000 subject concept classes and their relationships derived from [OpenCyc](/source/OpenCyc), which can act as binding classes to external data; also has links to 1.5 million named entities from DBpedia and [YAGO](/source/YAGO_(ontology))

### Datasets

- [DBpedia](/source/DBpedia) – a dataset containing extracted data from Wikipedia; it contains about 3.4 million concepts described by 1 billion [triples](/source/Semantic_triple), including abstracts in 11 different languages

- [GeoNames](/source/GeoNames) – provides RDF descriptions of more than 7,500,000 geographical features worldwide

- [Wikidata](/source/Wikidata) – a collaboratively-created linked dataset that acts as central storage for the structured data of its [Wikimedia Foundation](/source/Wikimedia_Foundation) sibling projects

- [Global Research Identifier Database](/source/Global_Research_Identifier_Database) (*GRID*) – an international database of 89,506 institutions engaged in academic research, with 14,401 relationships. GRID models two types of relationships: a parent-child relationship that defines a subordinate association, and a related relationship that describes other associations[24][25]

- KnowWhereGraph[26] – an integrated 12 billion triples strong [knowledge graph](/source/Knowledge_graph) of 30 data layers at the intersection between humans and their environment using Semantic Web and Linked Data technologies.[27]

- [Open ICEcat](https://en.wikipedia.org/w/index.php?title=Open_ICEcat&action=edit&redlink=1) [[uk](https://uk.wikipedia.org/wiki/Open_ICEcat); [nl](https://nl.wikipedia.org/wiki/Open_ICEcat)] - a [multilingual](/source/Multilingual) open catalogue containing product [datasheets](/source/Datasheets), related [digital assets](/source/Digital_assets) and usage [statistics](/source/Statistics).

### Dataset instance and class relationships

Clickable diagrams that show the individual datasets and their relationships within the DBpedia-spawned LOD cloud (as by the figures to the right) are available.[28][29]

## See also

- [American Art Collaborative](/source/American_Art_Collaborative) - consortium of US art museums committed to establishing a critical mass of linked open data on American art

- [Authority control](/source/Authority_control) – about *controlled headings* in library catalogs

- [Citation analysis](/source/Citation_analysis) – for citations between scholarly articles

- [data.gov.uk](/source/Data.gov.uk)

- [Hyperdata](/source/Hyperdata)

- [Network model](/source/Network_model) – an older type of database management system

- [Schema.org](/source/Schema.org)

- [VoID](/source/VoID) – Vocabulary of Interlinked Datasets

- [Web Ontology Language](/source/Web_Ontology_Language)

- [List of datasets for machine-learning research](/source/List_of_datasets_for_machine-learning_research)

## References

1. ^ [***a***](#cite_ref-DesignIssues_1-0) [***b***](#cite_ref-DesignIssues_1-1) [Tim Berners-Lee](/source/Tim_Berners-Lee) (2006-07-27). ["Linked Data"](https://www.w3.org/DesignIssues/LinkedData.html). *Design Issues*. [W3C](/source/W3C). Retrieved 2010-12-18.

1. **[^](#cite_ref-2)** ["Tim Berners-Lee on the next Web"](https://www.ted.com/talks/tim_berners_lee_the_next_web). [Archived](https://web.archive.org/web/20110410204952/http://www.ted.com/talks/tim_berners_lee_on_the_next_web.html) from the original on 2011-04-10. Retrieved 2009-03-15.

1. **[^](#cite_ref-3)** ["CSV on the Web Working Group Wiki"](https://www.w3.org/2013/csvw/wiki/Main_Page.html).

1. **[^](#cite_ref-4)** ["Frequently Asked Questions (FAQs) - Linked Data - Connect Distributed Data across the Web"](https://web.archive.org/web/20151118060145/http://linkeddata.org/faq). Archived from [the original](http://linkeddata.org/faq) on 2015-11-18. Retrieved 2014-12-29.

1. **[^](#cite_ref-5)** ["COAR » 7 things you should know about…Linked Data"](https://web.archive.org/web/20151118085816/https://www.coar-repositories.org/activities/repository-observatory/second-edition-linked-open-data/7-things-you-should-know-about-open-data/). Archived from [the original](https://www.coar-repositories.org/activities/repository-observatory/second-edition-linked-open-data/7-things-you-should-know-about-open-data/) on 2015-11-18. Retrieved 2015-12-29.

1. **[^](#cite_ref-6)** ["Linked Data Basics for Techies"](https://web.archive.org/web/20210505205603/http://openorg.ecs.soton.ac.uk/wiki/Linked_Data_Basics_for_Techies#Open_Linked_Data). Archived from [the original](http://openorg.ecs.soton.ac.uk/wiki/Linked_Data_Basics_for_Techies#Open_Linked_Data) on 2021-05-05. Retrieved 2015-12-29.

1. **[^](#cite_ref-7)** ["5 Star Open Data"](http://5stardata.info/en).

1. **[^](#cite_ref-8)** ["5-star Open Data"](https://5stardata.info/en/). *5stardata.info*. Retrieved 2021-03-07.

1. **[^](#cite_ref-9)** ["What is 5 Star Linked Data? | Webize Everything Community Group"](https://www.w3.org/community/webize/2014/01/17/what-is-5-star-linked-data/). *www.w3.org*. 17 January 2014. Retrieved 2021-03-07.

1. **[^](#cite_ref-10)** ["public-lod@w3.org Mail Archives"](https://lists.w3.org/Archives/Public/public-lod/).

1. **[^](#cite_ref-11)** ["SweoIG/TaskForces/CommunityProjects/LinkingOpenData/NewsArchive"](https://www.w3.org/wiki/SweoIG/TaskForces/CommunityProjects/LinkingOpenData/NewsArchive).

1. **[^](#cite_ref-12)** ["SIMILE Project - Mailing Lists"](https://simile.mit.edu/mail.html).

1. **[^](#cite_ref-13)** Linking open data cloud diagram 2014, by Max Schmachtenberg, Christian Bizer, Anja Jentzsch and Richard Cyganiak. [https://lod-cloud.net/](https://lod-cloud.net/)

1. **[^](#cite_ref-14)** ["SweoIG/TaskForces/CommunityProjects/LinkingOpenData - W3C Wiki"](https://web.archive.org/web/20091116123004/http://esw.w3.org/topic/SweoIG/TaskForces/CommunityProjects/LinkingOpenData). *esw.w3.org*. Archived from [the original](http://esw.w3.org/topic/SweoIG/TaskForces/CommunityProjects/LinkingOpenData) on 16 November 2009. Retrieved 22 March 2018.

1. **[^](#cite_ref-15)** Fensel, Dieter; Facca, Federico Michele; Simperl, Elena; Ioan, Toma (2011). *Semantic Web Services*. Springer. p. 99. [ISBN](/source/ISBN_(identifier)) [978-3642191923](https://en.wikipedia.org/wiki/Special:BookSources/978-3642191923).

1. **[^](#cite_ref-16)** Max. ["State of the LOD Cloud"](http://linkeddatacatalog.dws.informatik.uni-mannheim.de/state/). *linkeddatacatalog.dws.informatik.uni-mannheim.de*. Retrieved 22 March 2018.

1. **[^](#cite_ref-17)** ["Linked open data around the clock (LATC)"](https://web.archive.org/web/20180919095411/https://latc-project.eu/). *latc-project.eu*. Archived from [the original](https://latc-project.eu/) on 19 September 2018. Retrieved 22 March 2018.

1. **[^](#cite_ref-18)** Flatt, Amelie; Langner, Arne; Leps, Olof (2022), ["Model-Driven Development of AKN Application Profiles: Background and Requirements"](https://link.springer.com/10.1007/978-3-031-14132-4_2), *Model-Driven Development of Akoma Ntoso Application Profiles*, Cham: Springer International Publishing, pp. 5–12, [doi](/source/Doi_(identifier)):[10.1007/978-3-031-14132-4_2](https://doi.org/10.1007%2F978-3-031-14132-4_2), [ISBN](/source/ISBN_(identifier)) [978-3-031-14131-7](https://en.wikipedia.org/wiki/Special:BookSources/978-3-031-14131-7), retrieved 2023-01-07{{[citation](https://en.wikipedia.org/wiki/Template:Citation)}}: CS1 maint: work parameter with ISBN ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_work_parameter_with_ISBN))

1. **[^](#cite_ref-19)** ["Welcome to PlanetData! - PlanetData"](https://web.archive.org/web/20210421082019/http://www.planet-data.eu/). *planet-data.eu*. Archived from [the original](https://planet-data.eu/) on 21 April 2021. Retrieved 22 March 2018.

1. **[^](#cite_ref-20)** ["DaPaaS"](https://web.archive.org/web/20201218070059/http://project.dapaas.eu/). *project.dapaas.eu*. Archived from [the original](http://project.dapaas.eu/) on 18 December 2020. Retrieved 22 March 2018.

1. **[^](#cite_ref-21)** [Linking Open Data 2 (LOD2)](https://web.archive.org/web/20180929075540/http://lod2.eu/)

1. **[^](#cite_ref-22)** ["CORDIS FP7 ICT Projects – LOD2"](http://cordis.europa.eu/fetch?CALLER=PROJ_ICT&ACTION=D&CAT=PROJ&RCN=95562). European Commission. 2010-04-20.

1. **[^](#cite_ref-23)** ["LOD2 Project Fact Sheet – Project Summary"](https://web.archive.org/web/20110720164405/http://static.lod2.eu/Deliverables/LOD2_D12.5.1_Project_Fact_Sheet_Version.pdf) (PDF). 2010-09-01. Archived from [the original](http://static.lod2.eu/Deliverables/LOD2_D12.5.1_Project_Fact_Sheet_Version.pdf) (PDF) on 2011-07-20. Retrieved 2010-12-18.

1. **[^](#cite_ref-gridStats_24-0)** ["GRID Statistics"](https://grid.ac/stats). *grid.ac/stats*. Retrieved 2018-10-26.

1. **[^](#cite_ref-gridPol_25-0)** ["GRID Policies"](https://grid.ac/pages/policies). *grid.ac*. Retrieved 2018-10-26.

1. **[^](#cite_ref-kwg_26-0)** ["KnowWhereGraph"](https://www.knowwheregraph.org). *knowwheregraph.org*. Retrieved 2022-05-16.

1. **[^](#cite_ref-kwgaimag_27-0)** Krzysztof Janowicz; [Pascal Hitzler](/source/Pascal_Hitzler); Wenwen Li; Dean Rehberger; Mark Schildhauer; Rui Zhu; Cogan Shimizu; Colby K. Fisher; Ling Cai; Gengchen Mai; Joseph Zalewski; Lu Zhou; Shirly Stephen; Seila Gonzalez Estrecha; Bryce D. Mecum; Anna Lopez-Carr; Andrew Schroeder; Dave Smith; Dawn J. Wright; Sizhe Wang; Yuanyuan Tian; Zilong Liu; Meilin Shi; Anthony D'Onofrio; Zhining G; Kitty Currier (2022). ["Know, Know Where, Knowwheregraph: A Densely Connected, Cross-Domain Knowledge Graph and Geo-Enrichment Service Stack for Applications in Environmental Intelligence"](https://doi.org/10.1609%2Faimag.v43i1.19120). *AI Magazine*. **43** (1): 30–39. [doi](/source/Doi_(identifier)):[10.1609/aimag.v43i1.19120](https://doi.org/10.1609%2Faimag.v43i1.19120). [hdl](/source/Hdl_(identifier)):[1983/be176aba-9dec-456c-9615-01a0e8556b7b](https://hdl.handle.net/1983%2Fbe176aba-9dec-456c-9615-01a0e8556b7b).

1. **[^](#cite_ref-28)** ["Instance relationships amongst datasets"](https://web.archive.org/web/20121017231016/http://www4.wiwiss.fu-berlin.de/bizer/pub/lod-datasets_2009-07-14.html). *fu-berlin.de*. Archived from [the original](http://www4.wiwiss.fu-berlin.de/bizer/pub/lod-datasets_2009-07-14.html) on 2012-10-17. Retrieved 22 March 2018.

1. **[^](#cite_ref-29)** ["Class relationships amongst datasets"](https://web.archive.org/web/20110828103804/http://umbel.org/sites/umbel.org/lod/lod_constellation.html). Archived from [the original](http://umbel.org/sites/umbel.org/lod/lod_constellation.html) on 28 August 2011. Retrieved 22 March 2018.

## Further reading

- Ahmet Soylu, Felix Mödritscher, and Patrick De Causmaecker. 2012. ["Ubiquitous Web Navigation through Harvesting Embedded Semantic Data: A Mobile Scenario."](http://www.ahmetsoylu.com/wp-content/uploads/2013/10/soylu_ICAE2012.pdf) [Archived](https://web.archive.org/web/20180919092519/http://www.ahmetsoylu.com/wp-content/uploads/2013/10/soylu_ICAE2012.pdf) 2018-09-19 at the [Wayback Machine](/source/Wayback_Machine) Integrated Computer-Aided Engineering 19 (1): 93–109.

- *[Linked Data: Evolving the Web into a Global Data Space](http://linkeddatabook.com/book)* (2011) by Tom Heath and Christian Bizer, Synthesis Lectures on the Semantic Web: Theory and Technology, Morgan & Claypool

- [How to Publish Linked Data on the Web](http://wifo5-03.informatik.uni-mannheim.de/bizer/pub/LinkedDataTutorial/) [Archived](https://web.archive.org/web/20210419093458/http://wifo5-03.informatik.uni-mannheim.de/bizer/pub/LinkedDataTutorial/) 2021-04-19 at the [Wayback Machine](/source/Wayback_Machine), by Chris Bizer, Richard Cyganiak and Tom Heath, Linked Data Tutorial at Freie Universität Berlin, Germany, 27 July 2007.

- [The Web Turns 20: Linked Data Gives People Power](https://www.scientificamerican.com/article.cfm?id=berners-lee-linked-data), part 1 of 4, by Mark Fischetti, *[Scientific American](/source/Scientific_American)* 2010 October 23

- [Linked Data Is Merely More Data](https://web.archive.org/web/20120809091450/http://knoesis.wright.edu/library/publications/linkedai2010_submission_13.pdf) – Prateek Jain, [Pascal Hitzler](/source/Pascal_Hitzler), Peter Z. Yeh, Kunal Verma, and Amit P. Sheth. In: Dan Brickley, Vinay K. Chaudhri, Harry Halpin, and Deborah McGuinness: *Linked Data Meets Artificial Intelligence*. Technical Report SS-10-07, AAAI Press, Menlo Park, California, 2010, pp. 82–86.

- [Moving beyond sameAs with PLATO: Partonomy detection for Linked Data](https://web.archive.org/web/20180726135146/http://knoesis.org/library/resource.php?id=1718) – Prateek Jain, [Pascal Hitzler](/source/Pascal_Hitzler), Kunal Verma, Peter Z. Yeh, Amit Sheth. In: Proceedings of the 23rd ACM Hypertext and Social Media conference (HT 2012), Milwaukee, WI, USA, June 25–28, 2012.

- Freitas, André, Edward Curry, João Gabriel Oliveira, and Sean O’Riain. 2012. ["Querying Heterogeneous Datasets on the Linked Data Web: Challenges, Approaches, and Trends."](https://www.edwardcurry.org/publications/freitas_IC_12.pdf) IEEE Internet Computing 16 (1): 24–33.

- [Interlinking Open Data on the Web](https://web.archive.org/web/20070626121000/http://sites.wiwiss.fu-berlin.de/suhl/bizer/pub/LinkingOpenData.pdf) – Chris Bizer, Tom Heath, Danny Ayers, Yves Raimond. In Proceedings Poster Track, ESWC2007, Innsbruck, Austria

- [Ontology Alignment for Linked Open Data](https://web.archive.org/web/20180726135332/http://knoesis.wright.edu/library/publications/iswc10_paper218.pdf) – Prateek Jain, [Pascal Hitzler](/source/Pascal_Hitzler), Amit Sheth, Kunal Verma, Peter Z. Yeh. In proceedings of the 9th International Semantic Web Conference, ISWC 2010, Shanghai, China

- [Linked open drug data for pharmaceutical research and development](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3121711/) - J Cheminform. 2011; 3: 19. Samwald, Jentzsch, Bouton, Kallesøe, Willighagen, Hajagos, Marshall, Prud'hommeaux, Hassenzadeh, Pichler, and Stephens (May 2011)

- [Interview with Sören Auer, head of the LOD2 project about the continuation of LOD2 in 2011](https://www.community-of-knowledge.de/beitrag/the-hype-the-hope-and-the-lod2-soeren-auer-engaged-in-the-next-generation-lod/), June 2011

- [Linked Open Data: The Essentials](http://www.semantic-web.at/LOD-TheEssentials.pdf) [Archived](https://web.archive.org/web/20160604112313/http://www.semantic-web.at/LOD-TheEssentials.pdf) 2016-06-04 at the [Wayback Machine](/source/Wayback_Machine) - Florian Bauer and Martin Kaltenböck (January 2012)

- [The Flap of a Butterfly Wing](https://web.archive.org/web/20150110000748/http://semanticweb.com/the-flap-of-a-butterfly-wing_b26808) - semanticweb.com Richard Wallis (February 2012)

## External links

[Scholia](https://www.wikidata.org/wiki/Wikidata:Scholia) has a *topic* profile for ***[Linked data](https://iw.toolforge.org/scholia/topic/Q515701)***.

- [LinkedData](http://www.w3.org/wiki/LinkedData) [Archived](https://web.archive.org/web/20210509085505/http://www.w3.org/wiki/LinkedData) 2021-05-09 at the [Wayback Machine](/source/Wayback_Machine) at the W3C Wiki

- [LinkedData.org](https://web.archive.org/web/20200106144712/http://linkeddata.org/)

- [OpenLink Software white papers](https://web.archive.org/web/20120722075239/http://virtuoso.openlinksw.com/white-papers/)

v t e Semantic Web Background Databases Hypertext Internet Ontologies Semantics Semantic networks World Wide Web Sub-topics Dataspaces Hyperdata Linked data Rule-based systems Applications Semantic analytics Semantic computing Semantic mapper Semantic matching Semantic publishing Semantic reasoner Semantic search Semantic service-oriented architecture Semantic wiki Solid Related topics Collective intelligence Description logic Folksonomy Geotagging Information architecture iXBRL Knowledge extraction Knowledge management Knowledge representation and reasoning Library 2.0 Digital library Digital humanities Metadata References Topic map Web 2.0 Web engineering Web Science Trust Standards Syntax and supporting technologies HTTP IRI URI RDF triples RDF/XML JSON-LD Turtle TriG Notation3 N-Triples TriX (no W3C standard) RRID SPARQL XML Semantic HTML Schemas, ontologies and rules Common Logic OWL RDFS Rule Interchange Format Semantic Web Rule Language SHACL Semantic annotation COinS GRDDL Microdata Microformats RDFa SAWSDL Facebook Platform Common vocabularies BIBFRAME BIBO DOAP Dublin Core MODS/MADS FOAF Schema.org SIOC SKOS Microformat vocabularies hAtom hCalendar hCard h-feed hProduct hRecipe hReview

v t e Open data Concepts Linked data Open science data Open-notebook science By location Americas Canada US Asia Iran Europe France UK Open data projects Open energy system databases Open access - Open content - Open education - Open government - Open hardware - Open knowledge - Open science - Open source

Authority control databases International FAST National United States Czech Republic Spain Latvia Israel Other Yale LUX

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Adapted from the Wikipedia article [Linked data](https://en.wikipedia.org/wiki/Linked_data) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Linked_data?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.