Help:Subpages in the user and talk namespaces
The new Wikipedia software has support for namespace-dependent subpages. This means that you can create subpages by simply typing their name prefixed with a slash, e.g. [[/Archive]], in some, but not all namespaces. Furthermore, subpages in these namespaces provide automatic backlinks to the main articles, e.g. "Talk:snowplow/archive" would provide a backlink to "Talk:snowplow".
We support and encourage the creation of subpages in the user namespace, as they allow for better organization of personal content. We also allow the creation of subpages for archiving purposes in the Talk: namespace. You may in fact organize old talk pages in a quite sophisticated manner by creating subpages for previous debates, e.g. [[/debate about verb definition (late 2002)]].
Sub-pages in any other namespace may not be handled properly by the software.