Pages with a title beginning with "Appropedia:" are our "project space" - they are pages about Appropedia itself, i.e. about this wiki project. (This is standard practice in MediaWiki.)
E.g. Appropedia:Mission is Appropedia's mission, & Appropedia:About is about Appropedia, and Appropedia:Internships is about internships with Appropedia.
You can also link to such pages with "A:" instead of "Appropedia:".