Wikis such as AltWiki and Wikipedia are divided into namespaces. These can be seen by how they precede the subject of a page -- this Structure page, for instance, is in the AltWiki namespace, and is thus called AltWiki:Structure. Pages lacking a prefix namespace are the norm, however.
Pages that lack a namespace are the primary target of this project: they should directly deal with the subject matter of Alternate DBZ's world. They do not have to be written from an in-character point of view, although they may be if the writer wishes to take the effort.
Pages in the Rules namespace deal with the structural rules of playing in Alt -- things like power level, techniques, and training. These take an out-of-character view.
Pages in the AltWiki namespace, such as this one, are largely advisory in nature, defining Wiki policies and giving information about the project itself in order to assist writers. As such, most writers will not have reason to edit AltWiki pages -- such is usually the purview of the room staff of AltDBZ. It is by no means an absolute rule, though, so if a writer has good cause to edit one, it shall certainly not be held against them.
Pages in the Help namespace give guidance on how to use the wiki, such as how to use wikicode to mark up text with bold or link to other pages.
Pages in the User namespace are for the private use of the users to collect information in. A common use is for a user page that indicates whom a user is, in relation to AltDBZ.
Pages in the Category namespace are for linking together multiple pages of a single grouping. For instance, all pages having to do with Cardinal could be linked through the Category:Cardinal page.
Other namespaces are not currently in use, largely.