What is a canonical tag?
Essentially, a canonical tag determines for content-duplicate pages which is the original (and should rank) and which is the copy (the clone). Let’s take an example of an online shoe store. The store is quite search engine optimized, both in terms of content and technically and structurally. In the women’s shoe section, there are the following URLs:
- my-shop.com/womens-shoes/sports-shoes/brand/
- my-shop.com/brand/womens-shoes/sports-shoes/
Why would one do such a thing? Because users utilize both navigation paths when clicking through the pages of your online shop.
The SEO report (Organic Traffic) indicates that the second URL ranks better than the first, yet neither is optimal. The reason both do not rank optimally is that they compete against each other for the keywords. In SEO, this is referred to as cannibalization. The search engine cannot decide which page is better since both are nearly identical. Perhaps the second URL has slightly more emotional images, but the product range and thus the text are identical.
There are now two problems:
- Neither of the two pages really makes it to the top positions in the ranking.
- Neither of the two pages can be turned off because users use both equally at least when ‘browsing’.
Solution: The Canonical Tag!
It is known from the report that one of the two URLs (the first) ranks better than the other. Of course, you want to keep (and improve) the traffic from search engines, so you set the canonical on URL 1 and refer to URL 2. This gives the search engine the signal that URL 1 should exist, but is a ‘clone’ of the second URL and can therefore be ignored in the search engine index.
If this has been implemented correctly (see code example below), it should be noted that the search engines will make URL one disappear from the index. And URL two will receive significantly higher rankings and thus more traffic from the search engine.
Technical implementation of the canonical tag
On www.mein-shop.com/damenschuhe/sportschuhe/marke/ insert the following code in the head section:
<link rel="canonical" href="https://www.mein-shop.com/marke/damenschuhe/sportschuhe/" />
On www.mein-shop.com/marke/damenschuhe/sportschuhe/ insert the following code in the head section:
<link rel="canonical" href="https://www.mein-shop.com/marke/damenschuhe/sportschuhe/" />
Now you have the following situation:
- URL 1 refers in the Canonical to URL 2
- URL 2 refers to itself in the Canonical
“What, so simple?” – And yes, it is indeed that simple. Nevertheless, there are a few pitfalls that should be taken into account.
- It should be noted that there are no collisions of the XML sitemap. Only indexable content belongs here, and a canonical URL (in the example URL 1) does not.
- If it is a multilingual site, one should definitely ensure that the Canonical and Hreflang tag do not exclude or hinder each other.
- And if a URL has been set to noindex, then no canonical should refer to it.
- Canonical references to pages that deliver errors (example: 404 page) or to redirected pages send a technically incorrect signal to search engines.
In the event of one of the above-mentioned errors occurring, the search engine will completely ignore the instructions and try to find the “right path” on its own. One might assume that the AI of the search engines should be sufficient here – and it usually is. However, not always, and secondly, the machine will notice that there are erroneous signals and will prefer error-free competitors in the ranking.
- You can find the complete range of SEO services at Rheinwunder here.
- If you want to improve your index management and need support, then send us an email or call us at: +49 228 243 313 53
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