MediaWiki

MediaWiki is a free software suite (system) which is for wikis, i.e. WWW-based systems for collaborative development of interlinked documentation. More simply put, it provides a web site with content which the users can modify via their browsers. It was originally developed to run Wikipedia; it is now freely available, and many other wiki sites (including Citizendium) use it.

Technical concepts

Pages

Information in MediaWiki is organized into pages, which are the basic large-scale units of information. A page is roughly equivalent to a file in most operating systems. A page is a somewhat richer object than a plain file in these systems, because it has a history which is an integral part of it; the history records every single change made to a page, along with the identity of the person who made the change.

A WikiMedia page has nothing to do with pages in popular editors such as Microsoft Word, or the physical sheets of paper which are the progenitors of pages in editors. It has more of a connection to the concept of 'page' in the WWW, where it again means an integral unit of data - although without the additional 'history' semantics which the 'page' object has in MediaWiki.

Markup

MediaWiki uses a particular kind of markup - i.e. syntax for doing certain things. To link to another page (e.g. "foo"), a user needs to write [[foo]]; to produce text in bold font, it is necessary to write '''foo''', etc.

Note that is a totally different markup syntax from that used elsewhere, in particular HTML (the markup syntax used for WWW pages), and the syntax used by SMF, the most popular software suite for running online forums (which is about as ubiquitous in forums as MediaWiki is in wikis).

Namespaces

All the pages in a wiki are generally grouped into namespaces. E.g. "User:" pages are one namespace, "User_talk:" pages are another, "Talk:" pages are a third, and "Image:" is another. Depending on how the MediaWiki installation has been customized, there are about 20 all told, generally in pairs: "<foo>:" and "<foo>_talk:".

The end of the name of a namespace is usually delineated with ":" (see examples above), and the full name of a page in a Wiki is <namespace>:<page>, e.g. "Talk:Hokusai". The main namespace is special - a pagename with no "<namespace>:" refers to a page in the main namespace.

Note that "foo:name" and "bar:name" refer to separate pages, so [[User:Test]] and [[Talk:Test]] take you to separate pages.

Templates

Templates are a way of putting commonly used groups of MediaWiki and HTML markup in a page, and including those sequences (via a process called transclusion, which includes the contents of those pages on the pages which refer to the template). In MediaWiki markup, when a template is used, the reference to it looks like {{foo}}.

Subpages

A subpage is basically an ordinary MediaWiki page with a "/" in its title. Subpages, which have names of the form "Foo/Bar", are associated with a particular top-level page with the name consisting of the part of the name before the "/" (in this example, "Foo").

Other than being related to a particular top-level page, there is little difference in how they are handled by MediaWiki. (See this page for more details.

History

The original software running Wikipedia was called UseModWiki, developed by Clifford Adams. This was adapted in 2001 by Adams from the original CamelCase-style wiki links, like this:

UnitedStates

to support the current linking standard of two square brackets, like this

[[United States]]

later on in 2001, Magnus Manske rewrote the software in order to support a MySQL backend. Some months following that, Lee Daniel Crocker again rewrote the software, and it took on the form it largely continues to have today. The software was not named "MediaWiki" until 2003.