MOS:SELFREF
This guideline is about self-references and specifies which types of self-references should be avoided and which kinds are acceptable.  A self-reference in an article usually mentions Wikipedia directly or tells readers to take an action on Wikipedia, such as editing the article.

Although self-references within Wikipedia articles to the Wikipedia project should usually be avoided, there are exceptions.  Some examples of acceptable self-references are articles about Wikipedia, categories, and maintenance templates.

Types of self-reference

This Wikipedia article discusses ..., While Wikipedia is not a ..., Edit this page ... 
Mentioning that the article is being read on Wikipedia, or referring to Wikipedia policies or technicalities of using Wikipedia, should be avoided in the article namespace where it is unnecessary. If mentioning a policy is necessary to disambiguate article titles or subtopics, hatnotes can serve that purpose.

These types of self-references limit the use of Wikipedia as a free content encyclopedia suitable for forking, as permitted by our licenses. The goal of Wikipedia is to create an encyclopedia, not merely to perpetuate itself, so the articles produced should be useful, even outside the context of the project used to create them. This means that while articles may refer to themselves, they should not refer to "Wikipedia" or to the Wikipedia project as a whole (e.g. "this website"). And our readers already know this is an encyclopedia; it is not useful to insert content disclaimers, e.g., "While Wikipedia is not a dictionary ..." to an article on a jargon term.

Mentioning the Wikipedia community, or website features, can confuse readers of derived works. Unless substantially part of the article topic, do not refer to the fact that the page can be edited, nor mention any Wikipedia project page or process, specialized Wikipedia jargon (e.g. "PoV" in place of "biased"), or any MediaWiki interface link in the sidebar or along the top of the screen.

References that exist in a way that assumes the reader is using an encyclopedia, without reference to the specific encyclopedia (Wikipedia) or the manner of access (online), are acceptable. For instance, in the article on the Kobe Bryant sexual assault case, before the alleged victim's identification, it said that "Due to concerns over privacy, the name of the alleged victim is not being included in this article or at this time." That is a reference that makes sense on mirrors and forks and in print, and makes sense in a copy of Wikipedia that contains only the article space.  Similarly, many list articles explicitly state their inclusion criteria in the lead section. The template  can be used to mark such passages as intentional self-references that are generally printworthy and mirror-worthy, but which some reusers may wish to suppress. Other examples of permissible self-references of this sort include disambiguation links (the templates for which suppress their appearance in printed copies), and "See ..." cross-references (which may or may not be printworthy, depending upon whether they are inter-article; .

The templates that render self-referencing messages for the maintenance needs of developing articles, such as , , and , are unavoidable (and may permissibly include things like "Edit this page ..."), but articles should normally avoid self-referencing templates such as  and the others.

Note that ..., It is important to ..., What is ...?, Surprisingly ..., Of course ... 

Avoid "breaking the fourth wall" to address readers directly in an unencyclopedic tone, either instructional or opinionated.  This includes the pedagogical style of posing rhetorical questions to the reader (worst of all in headings). Neutral cross-references, e.g. , are permissible (and best done with the  template), but are often best reworded ().

Click here to see more (think about print) 

Although Wikipedia is not a paper encyclopedia, articles should be written in a manner that facilitates transmission in other forms such as print, spoken word, and via a screen reader. So terms such as "this article" are preferable to "this webpage", and phrases like "click here" should be avoided. In determining what language is most suitable, it may be helpful to imagine writing the article for a print encyclopedia.

Free content projects, such as this website ... (writing about Wikipedia itself) 

Articles about online communities may well discuss Wikipedia as an example, in a neutral tone, without specifically implying that the article in question is being read on—or is a part of—Wikipedia. In this framework, if you link from an article to a specific Wikipedia page, use external link style, so the link will make sense in any context.  The  template will do this for you.

Such pages may include:

 Articles where Wikipedia played a major role in the subject of the article, for example: Uncyclopedia
 Articles about prominent people involved in Wikipedia, for example: Jimmy Wales
 Articles about Wikipedia
 Articles where Wikipedia, or an individual incident related to it, is illustrative of the subject, such as virtual community, encyclopedia and Streisand effect

This article was criticized by ... (articles are about their subjects, not this website) 

Wikipedia is an encyclopedia, so its articles are about their subjects; they are not about the articles themselves. This means that even if an article itself becomes famous, that article should not report this about itself.

For example, a discussion of Stephen Colbert's call for vandalism of the Elephant article might be appropriately mentioned in the article on The Colbert Report, but not in the article on elephants, because elephants have nothing to do with Stephen Colbert. Protests regarding depictions of Muhammad in Wikipedia's Muhammad article are not addressed in that article (which is about the prophet Muhammad), but rather in the article Depictions of Muhammad.

A mention of Wikipedia by a notable person is unlikely to justify a mention in their Wikipedia article; such a mention would have to reflect its importance in the person's overall body of work. For example, a radio host mentioning that he read his Wikipedia biography is not normally an important event in his overall career. On the other hand,  the media attention surrounding John Seigenthaler's Wikipedia entry is now a notable event in his public life.

In templates and categories  
Self-references are sometimes found in the templates and the categories.  Some of these are necessary or intrinsic to the purpose of the page, as with disambiguation information at the top of category pages and in  templates, which encourage readers to edit the page.  Unnecessary self-references are not encouraged in templates or categories, due to the need of third-party users to either delete those templates or modify them to remove the Wikipedia references.  For example, all  templates should provide a list of related articles, but none of them should label these pages as "Wikipedia articles" or as "Related articles on this website".

When forced to use templates like this, you should use them in a way such that the article still makes sense when the template is removed, in order to facilitate automated removal.

Wikipedia project coordination pages should be under :Category:Wikipedia administration, not in categories that contain main-namespace articles by topic. (A small number of articles about Wikipedia are in the mainstream categories and this is OK.) User pages may be categorized under :Category:Wikipedians, but not in any of the subcategories under :Category:People.

Self-reference tools 

The self-reference template, , is used to mark pieces of text and links that wouldn't make sense on copies of Wikipedia. This gives the ability to programmatically remove all such references or transform them into external links. Thus, the end product can have all of its self-references removed automatically for users, such as forks and mirrors. This template is most often used as a hatnote template to help guide editors from an article to a related Wikipedia policy or guideline page in the Wikipedia project namespace.

Many hatnote templates that do contain helpful preset text and linking, such as  and , support a  parameter that gives them the same functionality as , making them better options in most circumstances.

In cases where a Wikipedia page should link to Wikipedia itself (for instance, at Wikipedia) and this link should be kept on mirrors, the format  can be used to write the link as external, rather than internal when outside of Wikipedia, to prevent it breaking in mirrors. For instance:  (made by {{srlink|Main Page|Wikipedia's Main Page}}) as opposed to Wikipedia's Main Page ([[Main Page|Wikipedia's Main Page]]).

See also 

 Help:Printing, includes a partial list of page elements that are hidden on printable versions of pages
 Wikipedia:Printability, an essay about the printworthiness of redirect pages
 Wikipedia:Cross-namespace redirects
 List of Wikipedia articles with self-references
 List of Wikipedia articles with circular references
  – Do not use articles from Wikipedia as reference sources
 Wikipedia:Double redirects