Canonicalization

Canonicalization is a method used to help prevent duplicate content issues and manage the indexing of URLs in search engines. Using canonicals appropriately can be hugely helpful for SEO.

Implementing the canonical tag link attribute “rel=canonical” is a signal to search engines about the preferred page for indexing, and will be followed in most cases when it is correctly implemented to an equivalent page.

The collected SEO Office Hours notes below provide detailed information and best practices (straight from Google’s own search experts) for using canonicals on your website.

Make Sure A Separate PWA is Canonicalised to Your Mobile Site

May 29, 2018 Source

Google won’t get confused between your main site and separate PWA as long as you have canonicalization in place.


Internal Linking Causes Google to Crawl Canonicalised Pages

May 29, 2018 Source

Check your internal linking if you see Google crawling canonicalised pages.


Hreflang Should be Included Between the Canonical Versions of Pages

May 18, 2018 Source

Including hreflang on paginated pages is fine but the most important thing is to include hreflang tags between the canonical versions of the page.


Parameter Handling Signals Are Stronger Than the Canonical Signal

May 15, 2018 Source

Google won’t blindly follow URL parameter handling set in GSC, but John says that this is a stronger signal than using canonicals.


Pages With ‘Submitted URL Not Selected as Canonical’ Message in GSC Won’t be Indexed

May 15, 2018 Source

If you see the ‘Submitted URL not Selected as Canonical’ message for a URL in Google Search Console, that means the page isn’t being indexed.


Use canonicalization Instead of Noindex for Duplicate Content

April 3, 2018 Source

John recommends using rel=canonical instead of noindex in order to deal with duplicate content in the best way. This way the signals from both page versions can be combined rather than dropping all the signals from the noindexed page.


AMP Pages Need to Have Canonical Tags

February 20, 2018 Source

AMP pages without a canonical tag run the risk of not being considered to be valid, as well as creating duplicate content issues.


Canonicalising to Redirects Can Increase Time Taken to Index Preferred Version

January 23, 2018 Source

Canonicalising to redirects can increase the time taken for Google to decide which version to index, especially if these pages aren’t identical. Google also looks at other signals such as internal linking and sitemap files to make this decision.


Canonicalization For Filter Results Pages Isn’t Recommended

January 9, 2018 Source

Canonicalization shouldn’t be used for filter pages. This is because canonical tags can be ignored and filter pages aren’t always the same as they have different types of results.


Related Topics

Crawling Indexing Crawl Budget Crawl Errors Crawl Rate Disallow Directives in Robots.txt Sitemaps Last Modified Nofollow Noindex RSS Fetch and Render