Wikidata

Wikidata
Name	Wikidata
Caption	A view of the Wikidata interface showing an item page.
Developer	Wikimedia Foundation
Launch date	29 October 2012
Content license	CC0 (data), CC-BY-SA (media)
Programming language	PHP, JavaScript, Lua
Alexa	▼ 1,200 (approx., as part of Wikimedia)

Wikidata. It is a collaboratively edited, multilingual, structured knowledge base operated by the Wikimedia Foundation. Serving as central storage for the structured data of its sister projects including Wikipedia, Wikivoyage, and Wikisource, it allows information to be shared and maintained consistently across all Wikimedia wikis. Launched in 2012, it has grown into one of the largest and most actively edited open knowledge graphs in the world, underpinning countless external applications in research, technology, and digital humanities.

Overview

Wikidata functions as a central repository for machine-readable factual data, storing items that represent concepts, entities, and objects. Each item is uniquely identified and can be described using labels, descriptions, and aliases in hundreds of languages, enabling true multilingual access. The data is primarily used to populate infoboxes and other dynamic elements within articles on the English Wikipedia and its sister projects in languages like German, French, and Japanese. By centralizing this data, it reduces maintenance duplication across thousands of individual wiki pages and improves consistency. The project is built on the principle of open data, releasing its entire dataset under a public domain dedication, which has fueled its adoption by major institutions like the British Library, Museum of Modern Art, and Google.

Structure and data model

The core of Wikidata is its item-entity model, where every distinct concept—such as Mount Everest, Marie Curie, or The Beatles—is represented by a unique item with a Q-number identifier. These items are connected through statements, which are structured claims consisting of a property, a value, and optional qualifiers and references. Properties, identified by P-numbers, define the relationship, such as P19 for "place of birth" or P569 for "date of birth". Values can be other items, strings, quantities, or coordinates, creating a vast, linked graph of knowledge. This model supports complex data types, including geographic coordinates for locations like the Eiffel Tower or Sydney Opera House, and temporal data for events like the Treaty of Versailles or the Apollo 11 mission.

Development and history

The project was conceived in 2012 by Wikimedia Deutschland and funded through donations from the Allen Institute for Artificial Intelligence, the Gordon and Betty Moore Foundation, and Google, Inc.. Development was led by a team including Denny Vrandečić and Markus Krötzsch, with the first edit made to the item for Douglas Adams. The initial phase focused on populating interlanguage links, followed by the rollout of infobox support to major Wikipedias. Key milestones included the introduction of arbitrary data access in 2013 and the deployment of the Lexicographical data extension to support dictionary data. The technical infrastructure relies on the Wikibase suite, developed alongside the project and now used by other organizations like the National Library of Wales and the Smithsonian Institution.

Uses and applications

Beyond powering Wikimedia projects, Wikidata's open dataset enables a vast ecosystem of external tools and research. It is queried extensively via the SPARQL endpoint of the Wikidata Query Service, which supports applications like the Reasonator visualization tool and the Scholia academic profile service. Cultural heritage institutions, including the Metropolitan Museum of Art and the Rijksmuseum, use it to publish and link their collection data. In artificial intelligence and natural language processing, it serves as a critical training resource for projects at Facebook AI Research and the Max Planck Institute for Informatics. It also feeds major services like Google's Knowledge Graph and the BBC's dynamic content systems.

Community and governance

Like all Wikimedia projects, Wikidata is primarily governed and edited by a global volunteer community, coordinated through online forums, mailing lists, and annual events like the Wikimania conference. Key policy decisions are made through community consensus on pages like Wikidata:Property proposal and Wikidata:Requests for permissions. The Wikimedia Foundation provides technical and legal support, while Wikimedia Deutschland continues significant development work. Specialized user groups, such as WikiProject Medicine and WikiProject Women in Red, organize to improve coverage in specific domains. Dispute resolution and vandalism fighting are managed through tools like RecentChanges and user oversight, similar to processes on Wikipedia.

Reception and impact

Wikidata has been widely praised in academic literature for advancing the state of open linked data and has become a foundational dataset for the Semantic Web. Studies from institutions like the University of Oxford and the Massachusetts Institute of Technology have analyzed its growth and quality. It has received awards such as the Open Publishing Awards for its innovation. Criticisms have focused on data quality issues, the complexity of its data model for new editors, and philosophical debates about the representation of controversial topics. Its impact is profound, enabling new forms of computational research in fields from history to genomics and setting a benchmark for collaborative knowledge engineering.

Category:Wikimedia Foundation Category:Knowledge bases Category:Open data