Com/widgets/blue/. But the very same information could be available at an unsightly URL like this when visitors apply item filters: illustration.com/widgets?colour=blue Hreflang tag #one could be the self-referencing entry In such a case. And the value in the rel attribute need to be “alternate” – it can't get replaced with https://e-bookmarks.com/story4409172/the-was-ist-canonical-tag-diaries