Breadcrumbs are a built-in feature of the software and are shown when the page being viewed is a subpage in a namespace with subpages enabled.
So it is. There is a Breadcrumbs extension, but it shows the route a user has taken through the wiki,
This is the true meaning of using breadcrumbs, isn't it?
rather than the hierarchy of the page they're viewing.
Yes. I've always thought that "breadcrumbs" should have been called YAH or "You Are Here".
Mark W.