In Mediawiki jargon, a namespace is that part of the Mediawiki database where all the data of a particular kind are stored. The main namespace contains all "normal" articles. The user namespace contains the personal pages of all users who have created one.
This definition applies to all wikis that use the MediaWiki software.
This software provides for 18 basic namespaces — the main space, where page names have no prefix, and 17 auxiliaries, each with its own prefix. In addition, there may be custom namespaces, with their own prefixes. They are like folders in a filing cabinet — or on your hard drive.
Basic namespaces in PangaWiki
The main namespace or article namespace is the encyclopedia proper (see Special:Allpages). It is the default namespace and does not use a prefix.
The Homepage is Main Page.
Techdoc (custom namespace in PangaWiki)
The technical documentation (Prefix: Techdoc) namespace contains articles about PANGAEA internals. It is for documentation and maintenance purposes. To view pages from this namespace you have to login using your PANGAEA login and you must be curator.
The Homepage is Techdoc:Main Page.
The user namespace (prefix User:) is a namespace that provides pages for PangaWiki users' personal presentations and auxiliary pages for personal use, for example containing bookmarks to favorite pages. If you see in the Special:Recentchanges list that the user named "Uwe Schindler" has updated some pages, this user name is a link not to Uwe Schindler but to User:Uwe Schindler.
The image namespace (prefix Image:, also called image description pages) is a namespace that provides info about images and sound clips, one page for each, with a link to the image or sound clip itself. See Special:Imagelist.
The MediaWiki namespace (prefix MediaWiki:) is a namespace containing interface texts such as link labels and messages. They are used for adjusting the localisation (i.e. local version) of interface messages without waiting for a new LanguageXx.php file to get installed. Each label and message has a separate page. Pages in this namespace are permanently protected and can only be changed by the administrator.
The Template namespace was formerly a part of the MediaWiki namespace. It is used to define a standard text or boxes such as infoboxes and navigation boxes. Such "templates" can then be added to pages, either a copy of the text itself at the time of adding (substitution), or as a reference (kind of a link) to the text at the time of viewing the page (transclusion). When using transclusion any change made in the template immediately changes how the template looks in all the pages that use the template.
The Category namespace contains categories of pages, with each displaying a list of pages in that category and optional additional text.
The Help namespace contains Help pages.
Except for special pages, each namespace has an associated talk namespace. The talk namespaces are designated by adding talk: to the normal prefix. For example, the talk namespace associated with the main article namespace has the prefix Talk:, while the talk namespace associated with the user namespace has the prefix User talk:. Most of the pages in the talk namespaces are used to discuss changes to the corresponding page in the associated namespace. Pages in the user talk namespace are used to leave messages for a particular user. The user talk namespace is special in that, whenever a user's talk page is edited, that user (if logged-in) will see a box saying "You have new messages" on the top every page that they view until they visit their talk page.
To view pages from this namespace you have to login using your PANGAEA login.
There are two virtual namespaces that do not relate to pages stored in the database: Special and media.
The Special: namespace consists of pages (called special pages) that are created by the software on demand, such as Special:Recentchanges. These pages can be linked as usual, like [[Special:Recentchanges]], except when they have parameters; then, the full URL must be given, like an external link.
The Media: namespace can be used to link directly to an image or sound clip, rather than to the image description page. See information above on the image: namespace.