What is a canonical tag?

A canonical tag (also known as "rel canonical") is a way of communicating to search engines that a specific URL is the master copy of a page. Using the canonical tag avoids the problems caused by displaying identical or "duplicate" content on multiple URLs. In practical terms, the canonical tag tells search engines which version of a URL you want to show up in search results.

image.png 47.35 KB

Why does canonicalization matter?

Duplicate content material is a complex subject, however while search engines like Google and Yahoo move slowly many URLs with identical (or very similar) content material, it may motive some of search engine marketing problems. First, if seek crawlers must battle through an excessive amount of replica content material, they will omit a number of your particular content material. Second, large-scale duplication can also additionally dilute your rating ability. Finally, even in case your content material does rank, search engines like Google and Yahoo can also additionally select out the incorrect URL as the "original." Using canonicalization allows you manipulate your replica content material.

The problem with URLs

You might be thinking "Why would anyone copy a page content to have it twice?" and mistakenly assumes that canonization is nothing to worry about. The problem is that as humans we tend to think of a page as a concept, like your home page. However, for search engines, each unique URL is a separate page. Meaning, that each URL acts as individual entity we have to take care of. A classic example would be a non-www URL and one with www added to it. Both would show the same content, but only one should rank.

For example, search engine crawlers might be able to reach your homepage in all of the following ways:

  • http://www.example.com
  • https://www.example.com
  • http://example.com
  • http://example.com/index.php
  • http://example.com/index.php?r...

To a human, all of those URLs constitute a similar page. To a search crawler, though, each similar page is a sort of URLs is a unique "page." Even on this constrained example, we are able to see there are 5 copies of the homepage in play. In reality, though, that is only a small pattern of the versions you may encounter.

Modern content material control systems (CMS) and dynamic, code-pushed web sites exacerbate the trouble even more. Many webweb sites routinely upload tags, permit a couple of paths (and URLs) to the equal content material, and upload URL parameters for searches, sorts, foreign money options, etc. You may also have lots of replica URLs to your web website online and now no longer even recognize it.

Canonical tag best practices

Duplicate content issues can be extremely tricky, but here are a few important things to consider when using the canonical tag:

1. Canonical links to the current page (= self-referencing) are okay

You can always point your canonical link to the current page, especially if you have other pages that reference to the same page, too. For example, you can have /page-1, /page-2 and /page-3 and each of them can point to /page-1 as canonical target. Often, this is causing some confusion with SEOs.

2. Proactively canonicalize your home-page

Since the homepage, i.e. your / page, can be reached trough a variety of URLs, its always a good idea to point to the "right" URL, so that Google and other Search Engines will be able to detect the correct version of it.

3. Monitor your auto-generated canonical links closely

Sometimes bad code causes a site to write a different canonical tag for every version of the URL (completely missing the entire point of the canonical tag). Make sure to spot-check your URLs, especially on e-commerce and CMS-driven sites.

We've seen it more often than we'd like to - bad code can lead to wrong canonical links. This happens mostly with multi-lingual pages or happens trough bugs in the code. We're somewhat experienced in finding these issues and if you are not sure how you can solve these things yourself, feel free to reach out. We're offering low rates for this kind of bugfixing if you send us a nice message. :)

4. Do not create chained linking and send clear signals to the Search Engine

No matter how good Google has become in the past years, if you purposely send out "mixed signals", Google and other Search Engines will have a bad time to correctly follow your canonical links. For example, you should not tell Page A that its canonical link is Page B, then tell Page B that its canonical link is Page C, and tell Page C again that its canonical tag is Page A. This will cause Google to eventually not rank your page at all, causing a loss of ranking for your content all together. Clear instructions for Google will help you to get the most out of your content.

5. Consider "near-duplicate" content carefully

When most people think of canonicalization, they think of exact duplicates. The canonical tag can be used on near-duplicates (pages with very similar content), but be careful. There's a lot of debate on this topic, but it's usually a good idea to use canonical tags for very similar pages, such as product pages, that only differ in currency, location, or some small product attribute. Please note that non-canonical versions of the given page may not be eligible for ranking in the Search Engine eventually. If the pages are too different, search engines may ignore this tag completely.

6. Canonicalize cross-domain duplicates

If you manage each web sites, you could use the canonical tag throughout domains. Lets say you're a publishing enterprise that frequently publishes the equal article throughout many individual websites or blogs. Using the canonical tag will cognizance your rating energy on simply one site only. Keep in thoughts that canonicalization will save you the non-canonical web sites from rating, so ensure this use suits your commercial enterprise case.

30x Redirects vs Canonical Tags

A main misconception about SEO canonical tags/links and redirects is that they are the same thing when in reality, they are not just technically completely different. A redirect will - as the name states - redirects a request to another location. A canonical link will not cause any redirection of any kind in the browser. Only the Google Bot and such will understand the canonical link, but a redirect will completely move the request to another location. We do that for our Service Pages in our website, for example, as we moved over from static content to dynamically managed content in the backend. We didn't wanted to lose the traffic for the serviced pages, so we created Permanent Redirects. However, we also implemented Canonical Links in these pages, to tell the Search Engines that these pages are "the right ones".

How to check and control your canonical tags for SEO

When trying to check your canonical tags, there is a number of options you have to check if you have the right SEO performance. Here is a little checklist for you:
  1. does "this" page have a canonical tag?
  2. does the canonical link point to the desired target page that I want to be ranked?
  3. are both pages able to be crawled and indexed by my robots? 
  4. Am I disallowing crawling for the page in my robots.txt file?

There are plenty of tools out there that can help you to better understand how your SEO works on your page. For example, we are using Ubersuggest. Its a relatively cheap tool to get the most out of your content.