Canonical tag is a markup inserted into the source code of web pages, indicating that they are original content. Search engines read this tag, which acts as a warning that this is the page to which the user should be redirected when performing a search.
Ranking a web page well is a constant challenge that many SEO professionals are dedicated to daily. As much as there is an understanding of what makes search engines easier to find, you also need to know what can get in the way.
The canonical tag is an important mechanism that helps in properly indexing these pages. Google’s algorithm seeks as much clarity as possible when it detects web pages.
If they somehow find that there is similarity between addresses, there may be an understanding of duplicate content , which undermines ranking . The canonical tag is a simple intervention that can help you avoid this problem.
To better understand the subject, in this content we will delve deeper into what is the canonical tag going through topics such as:
- What is canonical tag?
- Why use the canonical tag?
- How does the canonical tag work?
- When and how to use the canonical tag?
- How important is redirect?
- How does the canonical tag work for social networks?
- What are the best practices for using this feature?
- What are the most common canonical tag errors?
- What are the most frequently asked questions about the topic?
Read on and learn more!
What is canonical tag?
Canonical tag is a markup inserted into the code of web pages to define that they are original content . This tag serves directly to read search engine algorithms such as Google and Yahoo and serves as a warning that this is the page to which users should be redirected when searching on these sites.
It’s common to find the same pages, but with different URLs within the same site. These variations of address often happen naturally in website building, but can be detrimental when ranking the page.
The canonical tag shows the algorithm which priority is the original page that will be shown in search results.
Why use the canonical tag?
One of the big problems that a web page can have when it comes to ranking is being in a possible situation of duplicate content . In practice, they are just address variations, but they are found at different URLs. It’s usually something like:
- “site-address”;
- “site-address /index.html”;
- “site-address /home.aspx”.
If you are looking at page URLs, you have certainly noticed these variations, but also seen that they lead to the same place. However, this can be a problem for search engine algorithms.
After all, for them, the same content at different addresses represents page duplication, which leads to punishment and loss of rank.
To solve this, it’s simple: Just use the canonical tag on the original page . Thus, it will be shown in the results as the main one without flowing to the other address.
Using tag is critical to preserving the ranking of pages that are important to a Content Marketing or Digital Marketing strategy in general.
Google Actions
Recently, Google has been working to prevent sites from using unhealthy practices to rank high with different pages that have the same content.
To this end, the algorithms went through updates that enabled them to detect when there is this duplication . In this scenario, of course, there are many companies that do not use this possibility intentionally, but will have their ranking invariably penalized.
Thus, it is critical to have a check job done by SEO professionals constantly. This avoids involuntary duplication and makes the canonical tag be used to the best of its ability.
How does the canonical tag work?

In essence, you use the canonical tag just like a 301 redirect , where you tell the algorithm to go to another page. However, the canonical tag works for search engines only , allowing you to bring visitors to that page.
With the canonical tag you don’t allow pages with URL variation to be indexed, but allow the user to access them. If you use a 301 redirect, you will not allow access from either.
Thus, the canonical tag works as a way to optimize your SEO without compromising your visitors’ user experience.
When and how to use the canonical tag?
When search engines don’t identify which version of your content needs to be included or excluded from indexing, or when they don’t know which page to guide metrics like trust and authority, this is the time to use the canonical tag.
Of course, this confusion about the original content often reduces its relevance in the ranking . SEO professionals know how damaging this behavior is, so it is critical to always be aware of the different pages and access metrics they receive.
If your site creates multiple pages for the same content, the canonical tag must be used. Most often, this replication of different addresses is generated by print pages or even pages where only a few URL parameters are changed.
Applying the canonical tag
The canonical domain is first defined, that is, the search site – Google, Bing, Yahoo !, among others – will be informed that a particular URL is the preferred page indexing for your site.
It is important to remember that you must choose between the version with or without “www”. And then, when indexed, this domain will be used in search results as well as for future page crawls and updates.
Its application is quite simple – just use the references “rel” and “href” . Let’s assume the preferred URL is “site-address / institutional” . So, for this to be indicated to search engine robots, you must add a element to the head section of the pages:
- rel = “canonical” href = ”institutional / site-address” />.

When this activation occurs, it is certain that most users will come across this URL every search result the page appears.
How important is redirect 301?
Practice ensures that traffic, as well as search engines themselves, is directed to the correct destination. Code 301 will make these engines understand that the page has been moved to another location rather than detecting it as duplicate pages .
It is also recommended to use 301 redirect when aiming to redirect visitors from one domain to another . This need can happen when a company changes its name and, with the intention of preserving its customers and followers as much as possible, seeks to get them used to the changes rather than migrating completely.
In this case, you need to make sure that each of the old URLs points to the new domain on the respective pages where each new version of the content is located.
To be effective with these changes, there are a few other important points to keep in mind, such as:
- Keep Google informed of changes at all , meaning if you migrate to a new domain, you can change your address in your site settings through Google Webmaster Tools;
- ensure that the new domain is tracked by Googlebot ;
- Please make sure that old URLs are not blocked, because if so they will make redirection impossible;
- Stay tuned to see if visitors are encountering error 404 , although the ideal is to prevent the problem from occurring. One tip we have to help with this task is that you do the testing yourself, listing all URLs and accessing them through the Quick URL Opener . When detecting URLs that have errors, try to correct the problem as soon as possible.
How does the canonical tag for social networks work?
This variation in URLs can also happen on social networks , however, there is behavior that generates user questions related to Facebook and Twitter likes.
When there is more than one address for the same page on these platforms, the likes count only appears at the URL tagged with . Thus, the user can not see your like being counted on the page he visits.
What are the best practices in using this functionality?
In this work of applying canonical tags, the ideal is to implement a qualified work parameter that avoids Google penalties. Thus, there are some good practices that should always be ahead of the company’s SEO work. Check out!
Use lowercase letters in URLs
Because Google can treat upper and lower case URLs as two different URLs, prioritize the use of lowercase letters on the server, and then do the same at the address for your tags.
Use correct domain version (HTTPS or HTTP)
If you switched to SSL , do not use any URL other than “HTTPS” in your canonical tags. Doing so may theoretically lead to confusion and unexpected results. The same goes for the opposite: if you do not have an SSL certificate, use only “HTTP” .
Only use one canonical tag per page
This is simple: if you use more than one tag per page, Google ignores both and you get the ranking problem.
What are the most common errors in canonical tag?
When canonical tags begin to be applied by the inexperienced, it is very easy to fall into a series of misconceptions that can completely damage traffic . Therefore, it is essential to obtain as much information as possible before taking action.
Ideally, follow the recommendations of the search engines themselves that adhere to these tags or from true subject matter experts, in this case experienced webmasters. To avoid risk, check below some errors that can be avoided early on, ensuring a good experience with canonical tags.
Not understanding that canonical tags exist for a single purpose
Much of the trouble reported by beginners comes from forgetting one important detail: The strategy only serves to avoid duplicate content and nothing else !
With that in mind, avoid applying canonical tags for anything other than resolving duplicate content issues, as the chances of generating new problems are very high.
Applying rel = canonical to wrong places
For the technique to work, rel = canonical must be located in the section. Otherwise, if code is entered in the
section, for example, search engines simply ignore the reference. In addition to rendering the technique unusable, this can compromise the page’s HTML structure.
Not carefully checking the source code
More common than creating code templates ready to declare rel = canonical for the sake of speeding up the work, is to copy it without making any changes to the destination link ]. It’s like redirecting the user to a wrong page, putting the reputation of the site as a whole in check.
Using SEO plugins can also lead to issues of the same nature, such as the inclusion of two or more canonical statements in the same source code, and just as in cases where the reference is outside the head section, Search engines will also ignore your application.
Using canonical tags on non-duplicate pages
As explained in the first common error, the technique should only be applied to duplicate content . An example that is becoming classic is the use of canonical in articles that extend to other pages, making all pages refer to the first.
Thus, all the content of the pages after the first one will be lost precisely because it is not duplicate. In this case, it is recommended to use canonical tag to get the full view of all content – all pages.
What are the most frequently asked questions?
Finally, we separate a real FAQ about the most common questions SEO professionals and inexperienced people have when dealing with canonical tags. Check out the main ones below!
Is the canonical tag approved on PageRank?
Yes! According to Google, you decide the tag URL to consolidate this link to similar or duplicate pages. Search engines can thus have more concrete information for URLs .
Ultimately, it’s up to Google to decide how your URLs will be handled, but usually when the searcher respects their canonical tags, PageRank will be approved.
Why does Google ignore some tags?
This happens when the algorithm does not trust the accuracy of the reported tag . In this case, there is actually the behavior of skipping, but only on the understanding that the content between pages is not so similar.
Are canonical tags weaker than 301 redirect?
It turns out that tags are suggestions, while redirection is definitive. Google understands exactly this way, so there is a perception sometimes that canonical tags are less effective.
Can Canonical tags only work on duplicate pages or can they also be used on similar content?
Only for duplicate pages or with very similar content. Otherwise, as we have already discussed, Google will ignore the request for the tag.
What types of pages can be tagged with a different URL?
The following:
- multiple versions of a page to support different types of devices. For example, “site-address / news /” and “site-address / news /”;
- Parameters and session IDs . For example, “site-address / products? Category = dresses & color = green” or “site-address / dresses / cocktail? Gclid = ABCD”;
- A single page present in multiple subfolders of category . For example, “site-address / decor / pillows” and “site-address / bedding / cushions”.
The use of canonical tag can be a decisive feature in ensuring that sites are properly ranked without being harmed by Google’s algorithm. This ensures effectiveness in SEO parameters and helps, for example, to strengthen Content Marketing strategies.
With that in mind, take a look at our SEO best practices ebook!