Help:Namespaces

Pages on a MediaWiki wiki are grouped into collections called "namespaces", which differentiate between the purpose of the pages at a high level. Pages in certain namespaces can also have special properties or behave differently when they interact with other pages.

Namespaces are indicated in page titles by prefixing the page name with "namespace:", so the prefix ":" in this page's title ("") indicates that this page is in the namespace. Note, however, that colons and prefixes can also appear in page titles without indicating a namespace: The page "Foo:" is a page located in the mainspace because the namespace "Foo" does not exist. Similarly the page ":Foo:" is in the "" namespace.

Standard namespaces
The standard MediaWiki installation has sixteen namespaces which can contain user-generated content; there are also two special namespaces which contain pages created 'on the fly' by the MediaWiki software. The standard namespaces are organised in pairs, with each pair containing a 'subject namespace' and a 'discussion namespace'. The namespaces are numbered from zero such that all subject namespaces have even indices, and all talk namespaces have odd indices.

-2:
This namespace is an alias used for direct linking to media files: the link    :Wiki.png links to just the image rather than the image description page, which would be     :Wiki.png.

-1:
This namespace is used to group special pages, reports and interfaces that are generated 'on demand' by MediaWiki and which are not directly editable. It is not possible to create pages in this namespace except by modifying or extending the MediaWiki software.

0: (Main)
Namespace zero is the 'null' namespace, commonly called the "main namespace" or "mainspace". This namespace typically contains the bulk of the content pages in a wiki. This namespace generally has no special properties.

1:
The "Talk" namespace is the discussion namespace attached to the mainspace. It has no special properties.

2:
Each user has a corresponding page in the     namespace, which is linked to from edit histories, watchlists, recent changes, etc; wherever an individual user is uniquely identified. This page, and subpages of it, can be used by users to record information about themselves or to test and draft new content. Pages of the form "   :UserName/Foo.js" or "    :UserName/Foo.css" can only be edited by the user themselves or by administrators.

3:
This namespace is the talkspace associated with the     namespace. Pages in this namespace are mainly used to leave messages for particular users or inform them of discussions that may be of interest to them. To facilitate this, when a page "    :UserName" is edited, whenever the user 'UserName' loads a page, a notice is displayed at the top of the page informing them of the edit: You have new messages  ([ last change ]).

This notice continues to appear until the user loads their user talk page to read the message.

4:
This namespace is normally used for meta-discussions related to the operation and development of the wiki. It has no special properties.

5:
This is a talk namespace that is normally used for discussions related to the associated subject pages. It has no special properties.

6:
The     namespace is used to store metadata for images, videos, sound files and other media accessed via the      namespace. Each file has a corresponding page in the     namespace which is often used to hold licensing data. Linking directly to a page in this namespace instead includes the media file inline in the page:  right  produces the image to the right. See Help:Images for more details of this link syntax. To create an internal link to the file page, you need to add a colon to the front of the namespace:  right  produces    :Wiki.png. The standard MediaWiki installation has alias "Image" for     namespace - See Namespace aliases.

7:
This is a talk namespace that is normally used for discussions related to the associated media files. It has no special properties.

8:
The MediaWiki namespace is used to hold system messages and other important content. For instance, the page    :Vector-view-edit contains the text that fills the "Edit" tab at the top of every page. If that page exists, it overrides the default content, which is "edit this page". Similarly,    :Common.css is the system message which holds the CSS code that is loaded for all users for each page. It has the special property that the entire namespace is fully protected and can only be edited by administrators.

9:
This is a talk namespace that is normally used for discussions related to the associated system messages. It has no special properties.

10:
The     namespace is used to hold templates, blocks of text or wikicode that are intended to be transcluded into several other pages. To facilitate this it has the special property that it is the default namespace for transclusions: the wikicode   is equivalent to   .

11:
This is a talk namespace that is normally used for discussions related to the associated template pages. It has no special properties.

12:
The     namespace is usually used to hold help files, instructions and 'how-to' guides. It has no special properties.

13:
This is a talk namespace that is normally used for discussions related to the associated help pages. It has no special properties.

14:
The     namespace contains categories, dynamic lists of other pages. To facilitate this, linking directly to a category page does not output an inline link, but instead includes the page into the associated category page. So the code       :Help </tt> causes a category link to appear at the bottom of the page (at the bottom in the box marked "Categories"). Clicking on that link takes you to the category page, where this page is visible in the category list. To create an inline link to a category page, you need to add a colon to the front of the namespace:       :Help </tt> produces     :Help. See Help:Categories for more details on category link syntax.

15:
This is a talk namespace that is normally used for discussions related to the associated category pages. It has no special properties.

Identifying namespaces
There are a number of ways by which the namespace of a particular page can be identified:

The magic word  </tt> returns the value of the namespace the page is in.
 * Magic words

The JavaScript variable wgCanonicalNamespace</tt> contains the full namespace name. The variable wgNamespaceNumber</tt> contains the numerical index of the namespace.
 * JavaScript

The  </tt> tag of the HTML page output is given two CSS classes that vary by namespace: A class ns-#</tt>, where # is the index of the namespace, and ns-XXX</tt>, where XXX is "subject</tt>" for all subject namespaces, "special</tt>" for pages in the     namespace, and "talk</tt>" for talk namespaces. So CSS code such as the following can be used to change the appearance of an object based on its namespace:
 * CSS

You can get a complete list of all the namespaces used on this wiki from the API:
 * API
 * /w/api.php?action=query&meta=siteinfo&siprop=namespaces