If you are dedicated to website management, you are very clear how easy it is to run the risk of hosting duplicate content on your website: technical errors, product sheets to be re-proposed, pages that can be consulted from different URLs, are potential problems that risk making an unpleasant impression on crawlers responsible for identifying the original content.
In 2009, Google introduced the rel = "canonical" tag, a very valuable tool to indicate the preferred version of content.
The canonical relation is not only an aspect to examine to ensure a correct understanding of our web pages, but also a tool that we can use to possibly improve positioning.
This is not a difficult implementation to develop, but rather a resource that can be improved if it is understood in its complexity.
Fortunately, Google provides a page that answers the most common questions regarding duplicate content URLs.
So, let's find out everything there is to know in terms of actual duplicate and canonical content.
What is canonical rel?
If there is a web page on your site that can be accessed from different addresses, or if there are multiple pages that are very similar to each other, you run the risk of Google detecting duplicate content within your portal.
Content that is recognized as canonical is scanned by Google, while others will be considered duplicates and less crawled.
The canonical URL is the address of the page perceived as the most significant among the identical or very similar variants present: this also applies to pages located on different domains.
For example, we can have
www.sito.it
www.site/index.html
which correspond to the same page but which search engines may perceive as duplicates due to different URLs.
For example, if your company website has the page
site.it/categoria/prodottoX
and on the subdomain dedicated to that product category you have the identical content page
category.sito.it/prodottoX
you must set one of the two URLs as canonical.
The canonical attribute is, in fact, Google's preferred way to manage duplicate content and easily identify which are the unique routes to scan. The correct management of canonicals allows you to optimize the available resources and direct the popularity of the links towards those contents to be perceived as relevant and attribute authority in a unique way. This is not a directive, but rather “advice” that should be given to Googlebot to optimize crawling. In its "cross domain" version, it also allows you to unify the versions between the different domains to, for example, report product descriptions in the same form on multiple portals.
The rel=canonical allows you to resolve agenda items such as products that can be reached through different paths, for example the subcategory in which they are positioned and the promotion section when they are highlighted.
How to set the rel=canonical
To set the rel=canonical you simply need on the page to tag the "link" element with the "canonical" property with the address of the canonical page. The same canonical set just described must be repeated on the duplicate pages.
The formula is as follows:
link rel = «canonical» href = «http://www.sito.it/pagina-canonica/» />
If you work with CMS like WordPress or Joomla, you can manage these prompts through convenient plugins, for example Yoast.
The canonical rel differs from the 301 redirect in that the first is a crawl indication, while the second is a redirect that sends the crawler to another resource, so of the two, the more "powerful" is the redirect, since which has a physical effect.
The canonical can also be used for content belonging to different sites, referring to the absolute address of the page.
What happens if I don't set the canonical tag?
If you avoid clearly indicating which is the reference version of the page, Google will choose one at its discretion or will evaluate both with the same weight.
Rel canonical is, therefore, a way to optimize crawl budget resources and promote indexing on Google.
Why do canonical relays have to be configured correctly?
Google and search engines in general aim to find and catalog as many documents as possible on the web, but there are already many, and the undertaking requires a titanic effort. Also think about how many versions of the same pages exist: mobile and desktop versions, eCommerce product sheets replicated on reseller sites, technical errors leading to unwanted page copies of no value to the user.
To finalize its crawling capabilities, Google is keen to have identical versions of the same pages marked as such so that bots only enter them into files once. The easiest way is to directly read which page is marked as the main one, so that other identical pages automatically fade into the background.
Helping Googlebot filter out redundant pages is a good idea to allow the crawler to focus on the ones that are really useful to readers and neglect useless copy that would clog up the serp (assuming they get there without being filtered).
The best thing to do is direct 301 redirects to the main version of the page so that clicks on all versions return to the same content.
For example, we can do that:
mysite.com
mysite.com/index.html
mysite.com/index.php
always refers to
https://www.mysite.com
In this way we can make different addresses always refer to the same page.
The label must be added in any of those that have any duplicate content, for example the product sheets in the creation of ecommerce when:
- They are accessible from multiple URLs in the same store
- They are identical in content to those of the manufacturer
Other variants of the canonical ones are the rel = "previous" and rel = "next" links that indicate the pagination of the site, as in the case of category pages 1,2,3 and so on.
If you follow all these guidelines you can undoubtedly help Google understand the versions of the page to consider and avoid misinterpretations.
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