Warhammer 40k - Lexicanum:Namespace
Namespace is a technical Mediawiki term. A namespace is a set of Lexicanum pages whose names begin with a particular reserved word recognized by the MediaWiki software (followed by a colon). For example, in the user namespace all titles begin with the prefix "User:". In the case of the article (or main) namespace, in which Lexicanum articles appear, the reserved word and colon are absent. Namespaces serve to separate for example system pages from actual content pages.
In the Lexicanum currently the following namespaces exist:
From an end user point of view the main relevance of namespaces is to enable him/ her to filter lists (for example the Recent changes overview) by selecting (or excluding) the appropriate namespace(s) from the available list and to only see edits from specific namespaces, e.g. only see article discussions ("Talk") or only user discussions ("User talk") or only changes concerning files ("File") etc.
For more information on Mediawiki namespaces see here.