Search engines are getting smarter. There is little doubt about that. However, in a CMS-driven web where content can often exist on several URLs, it is not always clear what is the authoritative URL for a given piece of content. Also, having content on several URLs can lead to problems with link and ranking signals being split across several variations of a piece of content.
It is hard enough standing out in the often hypercompetitive search landscape, so you would imagine that most businesses had these foundational SEO issues under control. Unfortunately, our experience would tell us otherwise. In fact, it seems that in the wake of many sites moving towards HTTPS for the promised ranking boost, we are seeing even more issues of URL-based duplicate content than before.
Fortunately, we have the canonical tag. With rel=canonical, we can easily specify the authoritative URL for any piece of content. Google and the other engines will then consolidate link and rank signals for all variations of this content onto a single URL. This is, of course, if rel=canonical is correctly implemented.
In this article, I take a look at how incorrect implementation of canonical URLs can exacerbate URL-based duplicate content. I also share an example of a UK-based e-commerce store that recently saw their home page de-indexed (just the home page) due to what seemingly ended up being an issue with the canonical URLs.
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