The links on this page highlight themselves as appropriate. They will appear current (bold) when the current page address matches their link destination. As an example, the links below navigate to anchors within the page. As you navigate (by clicking, editing the address bar, going back/forward), the links will update their own current state.
A link of this type can also represent an area within a site, not just a single page. Such a link will be marked as current whenever the user is at a destination at or below the point in the navigational hierarchy indicated by the link's destination.