When adding wikicode while editing pages, certain "magic words" (sometimes called "reserved words" in programmer speak) do special things rather than just show up as they look normally.
Some commonly used examples of "magic words":
__NOTOC__ - suppresses automatic Table of Contents generation.
{{PAGENAME}} - inserts the current page name. As in: Magic words
{{PAGENAMEE}} - inserts the current page name in a wiki URL friendly form. As in: Magic_words
{{NAMESPACE}} - inserts the current name space name. As in: Help
A "magic word" is a keyword or phrase recognized by MediaWiki software (which Wikia is built on), which triggers the software to do something special on the page. When editing in the visual editor, magic words on the page will show up as a green puzzle piece.
To add a magic word, simply add the magic word to the content of the page somewhere. It will look like code, but after you save (or preview), it will work as intended.
Magic words can be added in either editor (source or visual), however, source mode must be used to edit a magic word. Alternatively, in the visual editor, you can simply remove the magic word you wish to change and add the new one.
Common Magic Words
Here are some of the magic words used most commonly at Wikia:
__NOTOC__ hides the table of contents on a page.
__TOC__ places the table of contents exactly where this is entered. It overrides the NOTOC switch.
#topusers# - Gets a list of the most active users.
Category Galleries
These magic words will apply to the Category Gallery feature when left on a Category page:
__NOCATEGORYGALLERY__ - Hides a category gallery from being rendered on a category page.
__FORCECATEGORYGALLERY__ - If the category gallery is enabled on a wiki, but it is not applied to all categories by default, this will add a category gallery to the category page.
Notes
↑{{SITENAME}} - like all others variables that give you meta information - is relative to the page you use it on. Since this is the Shared Help {{SITENAME}} will always say "Help Wiki" - no matter on which wiki you're viewing this page. You get the same effect if you use {{SITENAME}} in a template and transclude it from another wiki.
↑Some magic words may function differently, or not work, at Wikia.com. This occurs because the version of the mediawiki software used by Wikia is not always the same version as those of either MediaWiki.org or Wikipedia.org.