What are namespaces?
Namespaces are large “storages” that group pages according to their function. Placing a page in a namespace causes the MediaWiki software to treat it in a special way. For example, this page is in the Wookieepedia namespace, according to its prefix (Wookieepedia:FAQ). Every namespace except Special (whose pages are generated by scripts on the fly, rather than being stored in the database) has an appropriate talk namespace, unless it is itself a talk namespace. For example, the talk page for the article named Star Wars (located in the default namespace, without any prefix) resides at Talk:Star Wars.