A Wikipedia article or entry is a page on this site that has encyclopedic information on it. A well-written encyclopedia article:

• identifies a notable topic,
• summarizes that topic comprehensively,
• is written in an encyclopedic style of language,
• has been well copyedited,
• contains references to reliable sources, and
• contains wikilinks to and is linked to by other articles or article sections about related topics.

Most articles consist of paragraphs and images (perhaps with other types of audiovisual media). However, articles may also be formatted as stand-alone lists or tables (not to be confused with disambiguation pages, which are purely navigation aids). These lists or tables are also considered articles for Wikipedia's purposes and are included in the Main/Article namespace, the one without a title prefix followed by a colon (:).

The following items are not counted as articles (see also Wikipedia:Administration § Data structure and development):

• disambiguation pages,
• redirect pages,
• templates, including navboxes (aka navigation boxes),
• user pages,
• drafts,
• portals,
• talk pages (aka discussion pages),
• file pages for media such as images,
• category pages,
• help pages, and
• Wikipedia policies and guidelines pages (along with everything else in the Wikipedia: namespace).

See Wikipedia:Article titles to learn how we title articles.

Each article has a scope, which is what the article covers. The article should contain a readable summary of everything within the scope, given due weight, based on what reliable sources say.

Articles range greatly in quality, from as high as featured articles to as low as candidates for speedy deletion. Some articles are quite lengthy and rich in content while others are shorter (possibly stubs) or of lesser quality.

"Articles" belong to the main namespace of Wikipedia pages (also called "article namespace" or simply "mainspace").

The main namespace, article namespace, or mainspace is the namespace of Wikipedia that contains the encyclopedia proper – that is, where "live" Wikipedia articles reside, as opposed to sandbox pages.

The main namespace is the default namespace and does not use a prefix in article page names. This is distinct from other namespaces, where page names are always prefixed by an indicator of the particular namespace in which the page resides. For example, all user pages are prefixed by "User:", their talk pages by "User talk:", templates by "Template:", and various types of internal administrative pages by "Wikipedia:" (such as this page). Thus, any page created without such a prefix will automatically be placed in the article namespace.

The main namespace does not include any pages in any of the specified namespaces that are used for particular purposes, such as:

• the talk namespaces for discussing what the content of articles in mainspace should be (for example, Talk:Mathematics)
• the Wikipedia namespace, for material about meta subjects related to Wikipedia and is where policies and guidelines, essays, information, and process pages reside, as well as other "meta" topics about editing Wikipedia (examples, WP:VERIFY and Wikipedia:Statistics);
• the Wikipedia talk namespace, for discussing what the content of pages in Wikipedia space should be, and interpretations of them (for example, Wikipedia talk:VERIFY and Wikipedia talk:Statistics);
• the special namespace, whose pages are created by the software on demand (see Help:Special page);
• the user namespace for pages that are used by individual Wikipedia writers (example, User:Example).
• the file namespace which is used for describing and attributing images (example, File:Great Horned Owl.USFWS.jpg)
• the MediaWiki namespace, which is used to define shortcuts and other text strings used around Wikipedia (example MediaWiki:Wikimedia-copyrightwarning)

But not all pages in the article namespace are considered to be articles by everyone. Pages in mainspace that are not universally considered articles-proper are:

• hundreds of thousands of stand-alone lists (although these are usually treated as articles, and can even be assessed as featured lists) including outlines, glossaries and indices;
• hundreds of thousands of disambiguation pages and set index articles, which are used to resolve naming conflicts;
• many millions of redirect pages, including soft redirects, which are used to re-route one page to another page;
• and the Main Page, which is a portal – but it's still in mainspace from a time before any other namespaces existed, and it would be more trouble than it's worth to move it now.

Every page in the main namespace can have a companion talk page, and these belong to the "Talk" namespace, i.e., the page names start with the prefix "Talk:", followed by the name of the page in the main namespace. For example, "Talk:Wikipedia" is the talk page for Wikipedia's article on itself.

Special:AllPages has a list of all pages in the article namespace, and Wikipedia:Statistics has statistics on Wikipedia and its growth.

The automatic definition used by the software at Special:Statistics is: any page that is in the article namespace, is not a redirect page and contains at least one wiki link. The statistics software currently has no method of detecting disambiguation pages, however; nor does it disregard stubs (but in any case, many articles tagged as stubs are quite substantial) or stub lists (lists templates with little or no content).

• Wikipedia:Administration
• Wikipedia:Who writes Wikipedia?
• Wikipedia:Contributing to Wikipedia
• Wikipedia:Subpages
• Wikipedia:Featured article criteria
• What counts as an Article (from English Wikipedia's newsletter, The Signpost)

• Special:Statistics (current article count)
• More detailed (but less current) statistics