How-to 8 min read

How to use rel="canonical" tag for SEO

Dealing with pages duplication is one of the most important aspects of the site's optimization. Due to rel="canonical" tag, you can solve the problem of duplicated content providing the raising SEO efficiency. This tag indicates and priorities a canonical page among its copies within the one website.
Unoptimized content negatively influences the site's ranking. Availability of the master page provides correct notification the search engines about the existence of the similar or totally same ones.

Webmasters usually use 301 redirect as a method of solving the problem of duplicated content. However, this tool isn't always suitable for the following reasons:

  • a time-consuming process of the realization;
  • pages are regularly used by visitors.

How rel="canonical" works?

We know that using the canonical tag is one of the ways to deal with duplication. It can be placed on any HTML-page between <head> and </head> tags. Search engines start considering the tagged page priority. This page will be shown on the SERP.

If there are identical or extremely similar pieces of the content on your site which are under different URLs, the canonical tag will help you to mark the master page to be shown to search engines and users. Doing so, you help the search robots to understand which pages are to be ranked and which ones are considered additional.

Therefore, all the additional pages' characteristics are directed to the canonical page, e.g. links, visitors' behavior.
SEO Rel Canonical scheme for Google

Advantages of the rel canonical for SEO

Search engine robots have quite a negative attitude to the somehow duplicated content. They don't index identical text brought from either different websites or within pages under the same domain. Solving this issue is an essential aspect of effective internal site optimization.

Making the content noticeable for users provides raising visits and positively influences the site's conversion. Canonical URL can also refer to another domain if the content on these pages is the same. Canonical URL can also refer to another domain if the content on these pages is the same.
Rel canonical structure chart

How to set rel="canonical"

There are plenty of ways to set the canonical tag. Here are the most simple and common ways:

On the site's page (HTML-code)

This is a basic way which means pasting the rel="canonical" attribute to the code of the page. Important: the tag has to be placed in <head> </head> section. Provided you accidentally set the tag in the wrong section, the page won't be indexed by the search engines (will be simply ignored). Here is the code:
<link rel="canonical" href="http://your-website.com/canonical-page.html"/>

XML-site map

The canonical tag can be registered via XML-site map by the same token. However, in this case, there is a probability that search engines will ignore the tag.

Server's response

This option is suitable for non-HTML formats. For instance, if you need to index a PDF-document, you can add the rel="canonical" attribute to the http. In this case, the server will show the following thing:
Link: <http://your-website.com/main-file.pdf>; rel="canonical"
The only issue is that Google currently supports <link> element for web search only.

How to use rel="canonical"

Despite that this is a quite useful tag, using isn't always reasonable. There are several particular cases when the canonical pages are definitely needed:
Search in online-shops

Canonical is needed when different people look for the same goods using different search methods. For example, Person 1 is looking for a new pair of shoes by choosing the needed brand or model. At the same time, Person 2 can find the same shoes via setting a particular price or using the rating. Both of them enter pages with the same content, but, actually, their URLs are different.

To solve it, just choose one main page and refer all the other ones to it by tagging them with the canonical attribute.
<link rel="canonical" href="http://online-shop.com/tables.html"/>
Several goods of the one type

This situation is also about online-shops. When you have a particular number of the same goods differing only by a color. It is better to choose one of them as the canonical and bind other ones to it.
Loyalty program for clients

If there is a loyalty system on your site which includes bonuses, discounts, and special offers for frequent customers. Create links with rel="canonical" on pages for special clients and direct them to the standard ones.
Pages of the pagination

Pagination creates duplicate content. If there is a «View all» page on your site, refer all the connected URLs to it.
Work with the UTM

If you use the UTM to monitor the efficiency of your advertisement campaign then you need to remove doubles. Place the canonical link pointing at the basic page on the page which has the UTM.

How to choose a canonical page

Sometimes it's pretty hard to understand what exactly page should be considered the main. The page has to be the most suitable for indexation. In order to make the right choice, it is better to look at these two aspects:

  • page traffic;
  • number of the internal/external links.

How to adjust the rel="canonical" tag properly

Using canonical links webmasters make several typical mistakes which may cause serious problems and traffic loss. To avoid them you have to follow these rules:
One page — one rel="canonical" tag in <head> section.
Make sure that the tagged page has been indexed.
Don't complicate the link structure by building chains of the canonical URLs.
If you tag a page using several methods, be sure that all the links refer to the same page.
Choose absolute links instead of relative ones. It will minimize errors and prevent search engines from ignoring the pages:

Wrong: <link rel="canonical" href="shop.com/tables.html" />
Correct: <link rel="canonical" href="http://shop.com/tables.html" />


Due to the rel="canonical", you can manage doubling site's content and show to the search engines which pages are to be indexed. Sound use of this instrument positively influences the site's indexing, ranking, traffic and conversion as a result.

There are several methods of how to adjust the canonical reference. Choose the most suitable and appropriate for you one and pay attention to details in order to use the tag properly.

You may also like our partners' article:
Canonical Tags and Duplicate Content | The basics explained

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