The canonical tag is an HTML element that you can use in the pages of your website to prevent duplicate content, indicating with this Tag to the search engines your favorite page when you have pages with duplicate or very similar content.
We all know that search engines do not like sites with duplicate content, are usually of low quality or are trying to manipulate the rankings. It is worth mentioning that by saying “duplicate content” we do not only refer to a post on more than one page on your site or to the same product on several pages. It also counts as duplicate content having the same goal <title>, meta description, or headings in multiple pages of your site or even if your content is very similar to that of another website (so do not use content from other sites, even they can sue you).
Sometimes we come across sites that are not necessarily of low quality, and are not trying to manipulate the rankings, simply do not know this tag or do not have an expert to indicate how to use it. Unfortunately the search engines do not care about your intentions, and they will not forgive you simply because you ‘did not know’, you will suffer in the rankings if you neglect this technical aspect. This is very often seen with e-commerce sites, since they can have the same product on many pages, for example, pages with different URLs depending on how the user came to your product. Let’s see an example:
You sell clothes for men, and customers come looking for something specific, some cargo black shorts in size XL Dickies brand. A customer can search first by size, another customer can search first by category (shorts), and another customer can search first by brand. Other customers can search differently even using the ‘Search’ of your page. Each of these searches will give you a different URL, but the page will show you the same product, the same images, the same content of the whole page, this is duplicate content.
This is where the “link rel = canonical” tag fits perfectly, but where do you put it?
You have to choose a URL, and all other versions point to the one you chose, it is recommended that you choose the shortest, cleanest, and friendliest URL for the search engines and for your users.
Can I use the canonical tag on a page pointing to itself?
Yes, if you can use it in all your posts and pages pointing to itself, as long as there is no other page with similar content. Google has said that this does not affect you negatively and, in fact, it can help you if you have an automated system that steals your content, they take it with the canonical tag that means that your page is what search engines should prove by the content (clear as long as they are not removed).
Can I use the canonical tag for a series of paged search results?
This refers to when there is more than one page of products, using the example above we would have 3 pages of cargo shorts, black in size XL. NO, it is not recommended to use the canonical on each page pointing to itself. You can use it if you have an option to ‘see all’, then point to all others to that of ‘see all’, but even so it is not the most recommended. In these cases it is recommended to use ‘Pagination’.
In a blog, do I have the canonical tag in each post pointing to the main page of the blog, what do I do?
QUIT IT! As mentioned above, each post can have it pointing to itself (as long as there is no similar content on another page), or you can remove it from each post, but do not have it pointing to the main blog page. This would affect you negatively, since all your posts would not have authority, it’s like working for free for someone else.
A page with canonical pointing to another is indexed in Google?
No, when you use this tag you are telling Google that you have another preferred version, and that it does not take it into account. If Google sees your pages and says something like ‘no, yes, this guy applies it well here, I’m going to respect the tag’, then it’s as if the page pointing to the other one ceases to exist.
Do you have other doubts? Did something happen to me? Let me know