January 30 2023

What Is a Canonical URL & Why Is It Important?

canonical urlsCanonical URLs are an important part of SEO and if you are not up to date on its best practices, they can unknowingly have a negative impact on your website’s rankings. According to Google, the definition of a canonical URL is “the URL of the best representative page from a group of duplicate pages”. In other words, if there is a page for a vintage t-shirt (domain.com/vintage-t-shirt) that has a query string appended to it for available variations in black (domain.com/vintage-t-shirt?color=black), blue (domain.com/vintage-t-shirt?color=blue) and green (domain.com/vintage-t-shirt?color=green), a canonical URL will tell search engines to only index domain.com/vintage-t-shirt.
Without canonical URLs, search engines may penalize a site for having duplicate content, since the variations in the page may be very minimal. As sites grow and new pages are added, Canonical URLs are an important SEO checklist item. Let’s explore what you need to know about how and where to add canonicals to your site. 

Adding Canonical Code

When you use the HTML element “rel = canonical” in the header code of a web page, you are telling search engines like Google to reference a similar (sometimes exactly the same) page instead of that one. All of your webpages should have a canonical URL on them, but some might be self-referencing if there are no other variations. For this reason, the number of missing canonical URLs may be inflated for a site if you’re just referencing an SEO tool.
Most content management systems (CMS) have a field on each page to add the canonical URL, so adding them doesn’t require help from a developer. Most modern CMSs will auto-generate the code and put it in the right place on the page.

Where else can you specify canonical URLs?

  • HTTP header: This is the preferred method as it gives you the most control of indicating to Google which page should be indexed as the canonical URL. To do so, simply add the “rel=canonical” HTTP header response to the page(s) in which you would like to appear in search results.
  • XML ​Sitemap: The XML Sitemap indicates that each page should be indexed, but ultimately leaves it up to Google to determine which pages are duplicates and which are canonical URLs.
  • 301 redirects: By creating a 301 (permanent) redirect, Google will interpret the redirected page as a canonical. However, it’s important to understand that once you add a redirect, only the redirected URL will be visible to users.

How do canonical URLs improve SEO?

Canonical URLs help search engines like Google, better understand your website. By indicating to Google which pages should be crawled, you make it easier for Google to index your website as a whole. An accurately indexed website shows to search engines that you are good at maintaining your website, which is beneficial for your rankings.

Common Mistakes to Avoid

There are several mistakes that are often made when working with canonical URLs, the most common of which include:

  • Setting a canonical tag to a redirect page. Instead, set the URL to be the redirect target. This will avoid redirect loops.
  • Setting a canonical tag to irrelevant content: This will confuse Google and negatively impact your ranking.
  • Setting more than one canonical URL: If multiple are set, some or all of the canonical URLs will be ignored. Pick only one URL.

 Need help getting started, or just want to talk through a search engine optimization strategy that works? Feel free to reach out to a ZAG Interactive SEO specialist today.

  • SEO

posted by
Gabrielle Coburn
Gabrielle Coburn
Content Strategist

ZAG Interactive is a full-service digital agency in Glastonbury, CT, offering website design, development, marketing and digital strategy to clients nationwide. See current job openings.
Related Article
The Backbone of An SEO Strategy: Keyword Research