Standards
Wikidata item identifier (QID)
An identifier for a Wikidata item in a collaboratively maintained knowledge base.
- Kind
- Identifiers
- Steward
- Wikimedia Foundation; Wikidata community
- Official source
- https://www.wikidata.org/wiki/Wikidata:Introduction
What it describes
A Wikidata QID locates an item in Wikidata, a collaboratively edited knowledge base. Items can hold multilingual labels, descriptions, statements, qualifiers, references, and links to external identifiers. The QID makes it possible to refer to the item despite changes in its display label. It is particularly useful as a crosswalk among public datasets, provided the item represents the intended entity.
A QID is not independent verification of every statement attached to an item. Wikidata content can change, and one item can be split, merged, or corrected. For a consequential claim, follow the statement's cited source and revision history rather than citing the QID alone. Record the exact item and retrieval date when using it as a mapping hub.
Structure
The letter Q followed by a decimal integer.
Useful for
- Bridge external identifier namespaces.
- Resolve multilingual name variants.
- Inspect cited public statements.
Limits
- Community edits can change content.
- Statements vary in source quality.
- An item match still needs review.
How it is used in practice
Wikidata is a collaboratively edited knowledge base whose items have language-independent identifiers. An item can hold labels and descriptions in many languages, statements built from properties and values, qualifiers that scope those statements, references that cite sources, and links to identifiers in other systems. This makes it a common hub for matching: a researcher with an ORCID iD, a ROR ID and an LEI for the same organization can often find a Wikidata item that lists all three, and use it to move between them.
Statements carry ranks. A statement can be marked preferred, normal or deprecated, which lets the community represent that a value is current, that it is one of several, or that it is known to be wrong but worth recording. Data is released under a public-domain dedication and can be queried and downloaded, which is why it appears in so many pipelines.
A worked example
A fictional analyst builds a table of companies and wants a country of incorporation for each. For a company called Halden Therapeutics AG (fictional) the analyst finds a Wikidata item with a country statement. The statement has a reference, a stated-in source and a retrieval date, and a second statement with a different country that was deprecated with a qualifier explaining a past registration.
The analyst records the item, the statement used, its rank, the reference it cites and the date of the lookup. The company registry entry that the reference points to is then checked and cited as the primary source. The analyst's table cites the registry for the value and the Wikidata item for the discovery path. If the registry cannot be reached, the value is entered as unverified, with Wikidata as a pointer to be followed, not as a fact.
Evaluating a claim that rests on a QID
A QID identifies an item, not a truth. The first test is whether the item represents the entity you mean: items can conflate two things or split one, and descriptions are short. The second is whether the statement you need exists, has a reference and has an acceptable rank. Statements without references are the community's best current belief, and the project's verifiability policy asks for sources but does not guarantee that every statement has one.
The third test is stability. Items are edited continuously, and a lookup today can differ from one made last month. For consequential claims, record the item revision or retrieval date, and prefer the cited primary source when one exists. If an item is merged into another, the old QID redirects, so stored QIDs should be checked for redirects at refresh time.
Confusions to avoid
A QID is not an authority record in the sense of a registry. Nobody certifies it. It is a convenient and widely used identifier whose reliability varies by domain and item. In well-patrolled areas it can be excellent; in thin areas it can be a single editor's work.
It is also not a replacement for the identifiers it links. An LEI or an ORCID iD comes with its steward and rules. A Wikidata statement that connects an item to one of them is a claim about the link, with its own source. Treating the link as established because it appears in a hub hides the step at which a mistake would be introduced, and makes it impossible to say who asserted it.
Questions a reviewer can ask
Does the item represent the entity in the claim, judged by its label, description and linked identifiers? Does the needed statement carry a reference, and has it been checked against that source? What is its rank, and do qualifiers narrow its scope? Which revision or date was read? Has the item been merged or redirected since? Was the Wikidata value used only to find a primary source, or does the claim rely on it directly?
Related terms
Found an error on this page? See corrections for what counts as one, how to report it and the dated log.
Enquiry
Which of your sources carry Wikidata item identifier (QID)?
Tell us which sources carry it, which key the same entity some other way and who may read which. We reply with whether and how a first record would use this identifier.
Or write to [email protected] in your own words.