February 20 2018

What the Heck is a Canonical URL and Why Should I Care?

understanding canonical urlsThe concept of a canonical URL isn’t a new one, but its increasing importance in the SEO world makes it something that every digital marketer should understand. Why? Because as websites grow and change, it’s very common for there to be two or more versions of the same page. Since search engines dislike duplicate content, without explicitly telling them which version of a page they should index, they will crawl all of them. This will, in turn, penalize your rankings for those pages and hurt your overall SEO strategy. Enter the wonderful world of canonical code. By adding a canonical tag to a page, it tells search engines “hey, don’t crawl me, crawl my friend instead.” Sounds pretty simple, but the topic can get complex quickly, so learn what you need to know about canonicals, and why you should care.

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. It helps to organize your site from a behind the scenes way, which can help positively impact your SEO efforts.

The good news is that most site owners don’t need a web developer to add this code. Most content management systems (CMS) have a place on each page to add the canonical URL. Then the CMS will auto-generate the code and put it in the right place on the page.

Instances of Duplicate Content

As a responsible website owner, you may be wondering why you would have duplicate content and need this code? Well, it happens more often than you would think, and most of it is actually just for normal website usage. E-commerce websites are often hit the hardest with this because the different ways to filter products can create duplicate pages, but nearly every type of site will benefit from clearing up possible confusion. Common instances of duplicate site content can include:

  • Printable version of a page
  • Separate mobile versions of a page (if not responsive)
  • Session IDs or tracking information passing through the URL
  • Pages that must exist in multiple places for legal or marketing reasons
  • URL parameters

Beyond these more straightforward examples, if you have a series of similar articles or blogs on a topic on your site, Google will categorize them all and show you one version instead of listing the ten “copycat” versions. Why is this important to marketers and website owners? Because if you have this kind of duplicate content without establishing a canonical reference, your preferred version could be the one that’s cut from the results a user will see.  

Google uses Canonical URLs

When Google sees multiple instances of what it deems to be similar content, it will place a canonical reference in its index. In their own words:

“When Googlebot indexes a site, it tries to determine the topics covered in each page. If Googlebot finds multiple pages on the same site that seem to be about the same thing, it chooses the page that it thinks is the most complete and useful, and marks it as canonical. The canonical page will be crawled most regularly; the duplicates are crawled less frequently…

[When you indicate a page as canonical], Google uses [those pages] as the gold standard of your site's content, as far as evaluating content and quality, and the Google Search result usually points to the canonical page, unless one of the duplicates is explicitly better suited to a user's query: for example, the search result will probably point to the mobile page if the user is on a mobile device, even if the desktop page is marked as canonical.”

301 Redirects vs. Canonical Links

A 301 redirect (aka a permanent URL redirect) is similar to a canonical link, but with a major difference: 301 redirects send all traffic (human & bots) to the new URL. In contrast, a canonical link is just for the bots, so you can still track human visitors to any unique URLs or URL parameters which is relevant for website owners looking to track source traffic.

A 301 redirect is still an essential tactic for pages that have been retired, and you want to point them to a new URL permanently so that they keep any equity they previously had in search engines.

Implement Canonical Tags to Improve SEO

By explicitly marking the pages you want to list first with the canonical code, you are in control of your content and how it displays. In today’s race to the SEO top, it is a crucial tool as a base for all of your other efforts to stay on top of listings for your chosen keywords.

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
Rachel Avery Conley
Rachel Avery Conley

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.
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