In computing, linked data (often capitalized as Linked Data) is structured data which is interlinked with other data so it becomes more useful through semantic queries. It builds upon standard Web technologies such as HTTP, RDF and URIs, but rather than using them to serve web pages only for human readers, it extends them to share information in a way that can be read automatically by computers. Part of the vision of linked data is for the Internet to become a global database.
Tim Berners-Lee, director of the World Wide Web Consortium (W3C), coined the term in a 2006 design note about the Semantic Web project.[1]
Linked data may also be open data, in which case it is usually described as linked open data (LOD).[2]
In his 2006 "Linked Data" note, Tim Berners-Lee outlined four principles of linked data, paraphrased along the following lines:[1]
Tim Berners-Lee later restated these principles at a 2009 TED conference, again paraphrased along the following:[3]
Linked open data is linked data that is open data.[4][5][6] Tim Berners-Lee gives the clearest definition of linked open data in differentiation with linked data.
Linked Open Data (LOD) is Linked Data which is released under an open license, which does not impede its reuse for free.
Large linked open data sets include DBpedia and Wikidata.
The term "linked open data" has been in use since at least February 2007, when the "Linking Open Data" mailing list[8] was created.[9] The mailing list was initially hosted by the SIMILE project[10] at the Massachusetts Institute of Technology.
There are a number of European Union projects[when defined as?] involving linked data. These include the linked open data around the clock (LATC) project,[15] the PlanetData project,[16] the DaPaaS (Data-and-Platform-as-a-Service) project,[17] and the Linked Open Data 2 (LOD2) project.[18][19][20] Data linking is one of the main goals of the EU Open Data Portal, which makes available thousands of datasets for anyone to reuse and link.
Ontologies are formal descriptions of data structures. Some of the better known ontologies are:
There are a number of European Union projects[when defined as?] involving linked data. These include the linked open data around the clock (LATC) project,[15] the PlanetData project,[16] the DaPaaS (Data-and-Platform-as-a-Service) project,[17] and the Linked Open Data 2 (LOD2) project.[18][19][20] Data linking is one of the main goals of the EU Open Data Portal, which makes available thousands of datasets for anyone to reuse and link.
Ontologies are formal descriptions of data structures. Some of the better known ontologies are:
Clickable diagrams that show the individual datasets and their relationships within the DBpedia-spawned LOD cloud (as shown by the figures to the right) are available.[23][24]