Wikidata is a Wikimedia project to create an open and collaborative database. It is for data what Wikimedia Commons is for media files: it centralizes access and management of structured data, such as interwiki references and statistical information. Wikidata contains data in all languages for which there are Wikimedia projects. It is also deployed on Wikimedia Commons (since September 2013).
For more information, see Short introduction to Wikidata.
Wikimedia Commons on WikidataEdit
Information about Commons is stored in Wikidata in two forms: as sitelinks, and as statements on items.
Sitelinks identify a 1-to-1 mapping between Wiki-pages and items on Wikidata. They are added and edited in the lower part of the Wikidata page for an item. By convention, article-like items should only be sitelinked to gallery pages on Commons, and category-like items should only be sitelinked to category pages. The sitelinks are used to fill the interwiki links section in the page sidebar (though this can be over-ridden locally on the page). From December 2014, they will also identify the single Wikidata item from which information can be drawn by templates on a category or gallery page. (More flexibility in accessing information from Wikidata is hoped to be possible in Spring 2015).
Only Commons galleries and Commons categories should be sitelinked from Wikidata items, and then only from article-like and category-like items respectively.
The other way information about Commons is stored on Wikidata is through statements, which can be read by templates and programs which access Wikidata. These can be added and edited in the upper part of the Wikidata page for an item. Some of them are presented below:
Statements pointing to Commons pagesEdit
|Commons category||P373||String||name of the Commons category page (without the prefix "Category") containing files related to this article-like or category-like item|
|Commons gallery||P935||String||name of the Commons gallery page containing files related to this article-like or category-like item|
|Commons creator template||P1472||String||name of the Commons creator template (without the prefix "Creator") containing information related to this article-like item for a person|
|Commons institution template||P1612||String||name of the Commons institution template (without the prefix "Institution") containing information related to this article-like item for an organisation|
Statements pointing to media on CommonsEdit
|image||P18||Commons media file||an image depicting the subject (person, species, etc.); more specific properties should be used when more description is required, e.g. signature (P109), logo image (P154), locator map image (P242) and detail map (P1621)|
|video||P10||Commons media file||relevant video|
|audio||P51||Commons media file||a relevant sound|
|pronunciation audio||P443||Commons media file||audio media file on Wikimedia Commons with pronunciation|
|recording of the subject's voice||P990||Commons media file||audio file representing the voice of a person or character|
For a full list of properties with data type "commonsMedia" see list of properties on Wikidata, and sort by data type.
Properties relating article-like and category-like itemsEdit
|topic's main category||P910||Item||identifier for the category-like item that contains links to the category on Commons and the category on each Wikipedia which is considered the main category for the concept|
|category's main topic||P301||Item||identifier for the article-like item that contains links to the article on each Wikipedia which is considered the main article for the category. The identified item will also contain the link(s) to any related gallery page(s) on Commons.|