Why some items on Wikidata have no corresponding Wikipedia entry?

Question

I get stuck by this Wikidata item: 9., and wonder why there is no corresponding Wikipedia entry?

Answer 1

What can or cannot have an item is governed by Wikidata's notability policy:

1. It contains at least one valid sitelink to a page on Wikipedia, Wikivoyage, Wikisource, Wikiquote, Wikinews, Wikibooks, Wikidata, Wikispecies, Wikiversity, or Wikimedia Commons.
2. It refers to an instance of a clearly identifiable conceptual or material entity. The entity must be notable, in the sense that it can be described using serious and publicly available references.
3. It fulfills a structural need, for example: it is needed to make statements made in other items more useful.

So there can be items without Wikipedia articles if they correspond to some non-Wikipedia wiki page (e.g. a Wikisource source), they help extend the graph of Wikipedia items (e.g. relatives of a famous person who can be linked via child etc. relationships but aren't notable enough to have their own Wikipedia articles), or if those items refer to things or concepts which are discussed in serious sources (e.g. people tend to mass import things like authors from scientific databases).

Unicode characters presumably fall under the second point, the Unicode standard being a serious reference.

Answer 2

That's master data. Things that you need in order to refer to them in other entries.

Another example would be Q51155371. A meaningful encyclopaedic article is simply impossible.

You can however use the What Links Here tool to inspect if there are indeed references.

Answer 3

Wikidata is not limited to topics that are covered on the Wikipedias.

For instance, many hotels have a Wikidata item but no Wikidata article. Also, existing Wikipedia articles may be deleted or merged into others.

You can actually create new Wikidata items at https://www.wikidata.org/wiki/Special:NewItem without needing to reference any Wikipedia article.