Wikidata is a knowledge base that anyone can edit. Before you get started, it is a good idea to familiarize yourself with the Wikidata Glossary. That way, editors can "speak the same language" (so to speak). We hope that this will help to improve discussion and communication amongst editors.
Aliases are language-specific alternate names for items, properties and queries that can be used for lookup the same way as labels. Similar to the labels they are language specific, but unlike the labels there can be as many aliases as necessary.
Badge is a kind of marker put on sitelinks. They do not describe the external entity but the page on the specific site. For example a badge can identify the external page as being a featured article. (This is a future feature.)
|Constraint is a rule how a particular property should be used. For instance most identifiers should have only one value, so there is a single value constraint on them. |
Types (or datatypes) are how the information shall be stored in each claim. They are predefined and will be assigned to claims through the property they use. Types will be indicative and can be overridden if the definition of a property changes.
► Help:Data type
Description (approximately context, or a kind of key-phrase) is a language-specific additional context for the items, properties and queries. This is usually a descriptive phrase that gives a limiting context that makes the label conceptually unique for the user. For items it does not need to be unique, neither in the language or the overall project, but it must be unique together with the label. Uniqueness for a combination of a label and a description is a hard constraint that must be satisfied before a change can be saved, although it may be removed in the future.
Entity (also called topic, concept, or subject) is the real-life subject (or abstract concept) a page in Wikidata is about. This Entity is not the description itself, or the Wikidata or Wikipedia page: it is the topic, concept, or subject that the article describes.
|External identifier Some properties have values that are strings used in the databases of external organisations. They uniquely identify an item. For example, an ISBN for a book or the unique part of the URL of a movie or an actor in the Internet Movie Database.|
Item (also called topic, thing, or lemma) is what a page in Wikidata is about. An item is identified by its label and description (see Data model), by the Wikipedia articles linked to the page and by their own prefixed identifier. The item is not the entity, but the collection of data about the real world entity. An item can be viewed as the subject-part of a triplet in linked data.
Label (or name) is a language-specific name used for items, properties and queries. This is usually the most important name the entry is known under, or the most general or easily understandable phrase it will be known as internally to the project. Within Wikidata this takes the role of the title in Wikipedia and is used as the primary means to distinguish entries. For items it does not need to be unique, neither in the language or the overall project, but it must be unique together with the description. For properties and queries (not defined yet) it must be unique within the given language. Uniqueness for a combination of a label and a description is a hard constraint that must be satisfied before a change can be saved, although it may be removed in the future.
|Language attributes are the language-specific labels, aliases and descriptions that are attached to items, properties and queries. These are human-readable text to improve understanding of the scope of the item; for example the specific type of real world entity. If they are missing some of them can be replaced by strings from alternate languages, following the language fallback chains.|
|Language fallbacks (language chains) are methods to systematically replace missing language attributes with strings from alternate languages. The exact replacement rules can be chosen depending on the type of page, whether the user is logged in, or if so if the user has provided information about his preferred languages.|
MediaWiki is the software on which all Wikimedia projects are based. As the software is free, there are thousands of installations by different entities; see What is MediaWiki for more.
|Meta pages These are all pages that are not entities, i.e. do not belong to the data namespaces. Wikidata meta pages contain unstructured content represented by conventional MediaWiki code, and perhaps also future Wikidata client side inclusion code. Examples are talk pages, category pages, project pages (in the Wikidata namespace) and help pages (in the help namespace). Meta pages also comprise content and data automatically generated by the MediaWiki software (for example, the edit history of a page, or special pages).|
Namespace is a physical division of pages in MediaWiki to group them according to overall use or some additional behaviour. Examples are namespaces for categories, files, users, and in the case of Wikidata namespaces for items, properties and queries.
Page means a page or article in the main space of a wiki. In Wikidata there will be pages in different namespaces (just as in the Wikipedias). Pages in the main namespace of Wikidata will be about items, and one page can only hold one item.
|Project is a term often used in the Wikimedia movement. In most cases, people mean a Wikimedia Wiki. So in Wikidata, the term usually refers to Wikidata itself.|
Property (also called member, or field) is a smaller part of an item. A property is the descriptor for a value or set of values inside an item, but not the value or values themselves. Each property is described and defined on its own page, and have their own prefixed identifier. A property can be viewed as the predicate-part of a triplet in linked data.
|Qualifier is a part of the claim that says something about the specific claim, often in a descriptive way. A qualifier might be a term according to a specific vocabulary but can also be a variant descriptive phrase (if those terms or phrases are free text or part of some vocabulary would probably be up to the Wikidata community). |
Query is predefined search across items. A query is the descriptor for the predefined search, but not the hits generated by the search. Each search is described and defined on its own page, and have their own prefixed identifier.
► Wikidata:SPARQL query service
|Rank is a quality factor used for simple selection/filtering in cases where there are many statements for a given property. In such cases, you may want to indicate which statement is more important or relevant than other statements. By default, a statement has the rank "normal", but you can change this to either "preferred" or "deprecated". |
Reference (or source) describes the origin of a statement in Wikidata. A source is often an item in its own right; for example, a book. Wikidata does not aim to answer the question of whether a statement is correct, but merely whether the statement appears in a reference. What constitutes valid references is expected to be a question of debate among the Wikidata editors.
Site (siteid) is a reference to an external website in general, but in sitelinks it refers to specific registered websites that can be used for internal lookup. Those sites are referenced by global site identifiers or for short siteid. For example the English Wikipedia's siteid is
Sitelinks are special links that contain a site and a title, and go from individual items in Wikidata to pages on other sites such as Wikipedia. They are used both for identifying an item from an external site, and as a replacement for interlanguage links. Sitelinks can have attached badges and will usually show that a page has been a featured article, or of similar status.
|Snak is a technical term of Wikibase software which data users are most likely to encounter when accessing Wikidata through the MediaWiki API. It refers to the combination of a property and either a value or one of the special cases "no value" and "unknown value". Snaks can be found in claims (then they are called main snaks) or in qualifiers as part of statements (then they are called qualifier snaks). E.g., in the statement "Emma Watson was a cast member of Harry Potter and the Philosopher's Stone in the role of Hermione Granger" there is a main snak "was a cast member of Harry Potter and the Philosopher's Stone" and a qualifier snak "in the role of Hermione Granger".|
Statement (also called fact, claim, or triple, even though these are not completely correct) is one piece of data about an item, recorded on one page. In the simplest case, a statement is just a "property: value" pair (for example, "Location: Germany"), but often statements can have further qualifiers (such as temporal qualifiers). See Data model. Wikidata makes no assumptions about the correctness of statements, but merely collects and reports them with a reference to a source. The value of a statement can be viewed as the object-part of a triplet in linked data.
|String (also character string) is a general term for a sequence of freely chosen characters interpreted as text (e.g. "Hello") — as opposed to a value interpreted as a numerical value (3.14), a link to an item (e.g. |
Values (or datavalues) are the information pieces embedded in each claim. They can be a single value (like a number) or a value consisting of several parts (like a geopos with longitude and latitude). Internally they are connected to the claims through snaks.
Wikibase This is the software behind Wikidata. It consists of three MediaWiki extensions: Wikibase, Wikibase client, and WikibaseLib:
|Wikidata This Wikimedia project runs an instance of MediaWiki with the Wikibase extensions. It allows Wikidata editors to enter data and browse pages. |
Wikimedia is the name of a movement that provides free knowledge to the public through the Wikimedia projects.
Wikimedia projects are free wikis with a specific purpose, usually divided into multiple individual wikis for each language, as with Wikipedia. Wikidata is a multilingual Wikimedia project. There are about 800 different wikis in total for Wikimedia projects. As for now, only Wikimedia projects can be linked with Wikidata.