MediaWiki
What is it?
This wiki is powered by MediaWiki. You can see that logo on the bottom right of the screen. This is the framework that spun off from Wikipedia.
Extensions
Base MediaWiki is very feature rich. Extensions that were already included but just needed to be enabled were citations (with Cite), syntax highlighting (with SyntaxHighlight), and a fancier editor with quick preview support (with WikiEditor).
Extensions that I used which had to be installed were breadcrumbs, the kind that marks where you were (with JSBreadCrumbs).
Hidden
Unlisted would probably be a better name, but I implemented a way for pages to not show up in searches. These pages are not inaccessible but can only be accessible with a direct link. To do so, you can create a page with the namespace hidden in front of it. Easiest way to do so is go to your user page and add to your page Hidden:Page_Name replacing Page_Name with the name of your page, and save it.
Code added to the LocalSettings.php was the following:
define("NS_HIDDEN",3000);
define("NS_HIDDEN_TALK",3001);
$wgExtraNamespaces[NS_HIDDEN] = "Hidden";
$wgExtraNamespaces[NS_HIDDEN_TALK] = "Hidden_talk";
$wgNamespacesToBeSearchedDefault[NS_HIDDEN] = false;
$wgNamespacesToBeSearchedDefault[NS_HIDDEN] = false;