Wikipedia:Subpages

Except in the main namespace (article namespace), where the subpage feature has been disabled in the English Wikipedia, subpages are pages separated with a "/" (a slash) from their 'parent' page.

Making a new [[link]] that begins with a / (slash) is the common way to start a subpage. The page to which this link points is considered "subordinate" to its host page, and is titled and linked as [[Parentpage/Subpage]]. It is possible to create a subpage of a subpage (or a sub-subpage). At the top of each subpage or sub-subpage, you can find a backlink (a.k.a. breadcrumb) to the higher levels of the page.