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What is a Canonical Tag?

A Canonical tag tells search engines like Google that a certain URL is the master copy of a page. Its use prevents problems caused by identical or “duplicate” content on multiple URLs. In practice, the canonical tag tells search engines which version of a URL to display in search results.
  • Is a technical solution against duplicate content
  • Solves the problem “Same content – multiple URLs”
  • Important for SEO because it informs the search engines

Why is a Canonical Day important?

Duplicate content is a hot topic for webmasters, because if search engines crawl many URLs with identical (or very similar) content, this can lead to a number of SEO problems. First, search crawlers that have to crawl too much duplicate content may miss some of your unique content. Second, large-scale duplication can affect your ranking ability. Finally, even if your content is ranked, search engines may select the wrong URL as the “original”. By using Canonical Tags you can control duplicate content. The problem is that people tend to think of a page as a concept, such as a home page. However, for search engines, each unique URL is a separate page. To a human, all these URLs represent a single page. To a search crawler, however, each of these URLs is a unique “page”. Even in this limited example, you can see that five copies of the home page are in play. But this is only a small selection of the variations you might encounter. Modern content management systems (CMS) and dynamic, code-driven websites exacerbate the problem even more. Many web pages automatically add tags, allow multiple paths (and URLs) for the same content, and add URL parameters for searches, sorting, currency options, etc. A Web page might contain thousands of duplicate URLs that are not even recognized.

Canonical day in practice

Problems with duplicate content can be extremely difficult. When using the Canonical Tag, there are some important points to consider. So what can you do? Always canonicalize your homepage proactively. Given that homepage duplicates are very common and that people can link to your homepage in many ways (which you cannot control), it is usually a good idea to add a Canonical Tag to your homepage template to avoid unforeseen problems. Also check your dynamic canonical tags. Sometimes incorrect code will cause a site to write a different canonical tag for each version of the URL. Make sure you always check your URLs carefully in this regard, especially on e-commerce and CMS-driven websites. Also avoid mixed signals. Search engines can avoid a canonical tag or misinterpret it if you send mixed signals. In other words, dont canonicalize page A -> page B and then page B -> page A. Always send clear signals or you will force search engines to make bad decisions. Also, be careful when canonizing “almost” duplicate content. Instead of Canonical Tag the term Canonical URL is often used. When a website grows larger, it is often difficult to prevent pages from being duplicated or almost duplicated. This can lead to problems with duplicate content. If you have two similar pages and both are eligible to rank for a particular key phrase, the search engine simply does not know which of the two URLs to send traffic to. To solve this, you can select a preferred URL, which we call the Canonical URL. This “canonical URL” is a technical solution for duplicate content. For example, you may have a post or product that is attached to two categories and is available at two URLs. Canonical tags also allow you to refer search engines to the original version of an article. For example, suppose you have written a post for another party that is published on their website. If you want to publish it on your website as well, you can use a Canonical Tag to link to the original version.

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