Manual:$wgArticle

From MediaWiki.org

Global object: $wgArticle
Article object (or child object of Article) corresponding with Title object
Parameters:	$title
Class:	Article
Located in:	Article.php, CategoryPage.php, or ImagePage.php

[edit] Details

The Article object encapsulates access to the "page" table of the database. The object represents an article, and maintains state such as text (in Wikitext format), flags, etc.

The CategoryPage and ImagePage objects are child objects of the Article object, and are used specifically for Category pages and Image pages.